How to Work with PHP Arrays: a Complete Guide

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By squashlabs, Last Updated: September 13, 2023

How to Work with PHP Arrays: a Complete Guide

Introduction to Arrays

Syntax and structure, associative arrays, numeric arrays, multidimensional arrays, functions: explode, functions: implode, determining array length, the array push function, converting array to string, adding elements to an array, printing arrays, usage of array_map, looping through arrays, applying array_filter, conversion from objects to arrays, checking array for specific values, searching within an array with array_search, conversion from json to array, conversion from xml to array, merging arrays with array_merge, retrieving the last element of an array, retrieving the first element of an array, use case: data manipulation, use case: data validation, best practice: naming conventions, best practice: array size limitations, real world example: data analysis, real world example: user input handling, performance consideration: memory usage, performance consideration: processing time, advanced technique: nested loops, advanced technique: dynamic array creation, code snippet: basic array operations, code snippet: multidimensional array usage, code snippet: array search methods, code snippet: array conversion techniques, code snippet: array manipulation functions, error handling: common mistakes, error handling: debugging tips.

Table of Contents

Arrays are an essential data structure in PHP that allow you to store multiple values in a single variable. They are versatile and can be used to store different types of data, such as numbers, strings, or even other arrays. Arrays in PHP are ordered, meaning that the elements are assigned a numeric index starting from 0. This index allows you to access and manipulate the elements within the array.

Here’s an example of how to create a simple array in PHP:

In the above example, we have created an array named $fruits that contains three elements: “apple”, “banana”, and “orange”. Each element is assigned a numeric index, starting from 0.

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The syntax for creating an array in PHP is straightforward. You can either use the array() function or the shorthand [] notation. Here are a few examples:

Using the array() function:

Using the shorthand [] notation:

You can also assign values to specific indices within an array. For example:

In this case, we are explicitly assigning values to the indices 0, 1, and 2.

Associative arrays in PHP allow you to assign specific keys to each element instead of relying on numeric indices. This provides more flexibility and allows you to access elements using their corresponding keys. Here’s an example:

In the above example, we have created an associative array named $student with three key-value pairs: “name” => “John Doe”, “age” => 20, and “university” => “Example University”. To access individual elements, you can use the corresponding keys:

Numeric arrays are the most common type of arrays in PHP. As mentioned earlier, each element in a numeric array is assigned a numeric index starting from 0. Here’s an example:

In the above example, we have created a numeric array named $numbers with five elements: 10, 20, 30, 40, and 50. To access individual elements, you can use their corresponding indices:

Related Article: PHP Date and Time Tutorial

Multidimensional arrays in PHP allow you to store arrays within arrays, creating a nested structure. This is useful when you need to represent complex data structures. Each nested array can have its own set of keys and values. Here’s an example:

In the above example, we have created a multidimensional array named $students . Each element of the array is an associative array representing a student’s name and age. To access individual elements, you can use both the outer and inner indices:

The explode() function in PHP allows you to split a string into an array based on a specified delimiter. This is useful when you have a string with multiple values separated by a common character or sequence. Here’s an example:

In the above example, we have a string $fruits that contains the names of fruits separated by commas. By using the explode() function, we split the string into an array named $fruitsArray using the comma as the delimiter. Now, each fruit name is stored as a separate element in the array.

To access individual elements of the array, you can use the numeric indices:

The implode() function in PHP is the opposite of the explode() function. It allows you to join the elements of an array into a string, using a specified delimiter. Here’s an example:

In the above example, we have an array $fruits that contains the names of fruits. By using the implode() function, we join the elements of the array into a string named $fruitsString , with each fruit name separated by a comma and a space.

Related Article: How To Add Elements To An Empty Array In PHP

To determine the length or size of an array in PHP, you can use the count() function. This function returns the number of elements in an array. Here’s an example:

In the above example, we have an array $fruits that contains three elements. By using the count() function, we determine the length of the array and store it in the variable $length .

The array_push() function in PHP allows you to add one or more elements to the end of an array. This is useful when you need to append new elements dynamically. Here’s an example:

In the above example, we have an array $fruits that initially contains two elements. By using the array_push() function, we add two more elements, “orange” and “grape”, to the end of the array.

To convert an array to a string in PHP, you can use the implode() function, as mentioned earlier. This function allows you to join the elements of an array into a string using a specified delimiter. Here’s an example:

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In PHP, you can add elements to an array by assigning a value to a specific index or by using the array_push() function. Here are a few examples:

Adding an element using index assignment:

In this example, we add a new element “grape” to the array $fruits by assigning it to the index 3.

Adding an element using array_push() :

In this example, we add a new element “orange” to the end of the array $fruits using the array_push() function.

Adding multiple elements using array_push() :

In this example, we add two new elements, “orange” and “grape”, to the end of the array $fruits using the array_push() function.

To print the contents of an array in PHP , you can use the print_r() function. This function displays the elements of an array in a human-readable format. Here’s an example:

In the above example, the print_r() function is used to print the contents of the array $fruits . Each element is displayed with its corresponding index.

The array_map() function in PHP allows you to apply a callback function to each element of an array and return a new array with the modified values. This is useful when you need to perform a specific operation on each element of an array. Here’s an example:

In the above example, we have a function square() that takes a number as input and returns its square. By using the array_map() function, we apply the square() function to each element of the array $numbers and store the results in the array $squaredNumbers .

To access the modified values, you can use the numeric indices:

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Looping through arrays in PHP allows you to perform operations on each element of the array. There are different ways to loop through arrays, such as using the foreach loop or the traditional for loop. Here are a few examples:

Using the foreach loop:

In this example, we have an array $fruits that contains the names of fruits. By using the foreach loop, we iterate over each element in the array and print its value.

Using the traditional for loop:

In this example, we have an array $fruits that contains the names of fruits. By using the for loop, we iterate over each index of the array and print the corresponding element.

The array_filter() function in PHP allows you to filter an array based on a specified callback function. This function creates a new array that contains only the elements for which the callback function returns true. Here’s an example:

In the above example, we have a function isEven() that checks if a number is even. By using the array_filter() function, we apply the isEven() function to each element of the array $numbers and create a new array $evenNumbers that contains only the even numbers.

To access the filtered values, you can use the numeric indices:

In PHP, you can convert objects to arrays using the get_object_vars() function. This function returns an associative array that contains the object’s properties and their values. Here’s an example:

In the above example, we have a class Person with two properties: $name and $age . We create an instance of the Person class named $person . By using the get_object_vars() function, we convert the $person object to an associative array named $personArray .

To access the properties of the object in the array, you can use the corresponding keys:

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To check if an array contains specific values in PHP, you can use the in_array() function. This function searches for a given value in an array and returns true if the value is found, or false otherwise. Here’s an example:

In the above example, we have an array $fruits that contains the names of fruits. By using the in_array() function, we check if the value “banana” is present in the array. If it is found, the message “Found” is displayed; otherwise, the message “Not found” is displayed.

The array_search() function in PHP allows you to search for a specific value within an array and returns its corresponding key if found. If the value is not found, it returns false . Here’s an example:

In the above example, we have an array $fruits that contains the names of fruits. By using the array_search() function, we search for the value “banana” within the array and store its corresponding key in the variable $key .

If the value is not found, the array_search() function returns false .

In PHP, you can convert a JSON string to an array using the json_decode() function. This function takes a JSON string as input and returns an associative array representing the JSON data. Here’s an example:

In the above example, we have a JSON string $jsonString that represents a person’s name and age. By using the json_decode() function with the second parameter set to true , we convert the JSON string to an associative array named $dataArray .

To access the values in the array, you can use the corresponding keys:

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To convert an XML string to an array in PHP, you can use the simplexml_load_string() function along with the json_encode() and json_decode() functions. Here’s an example:

In the above example, we have an XML string $xmlString that represents a person’s name and age. We first load the XML string using the simplexml_load_string() function, which returns a SimpleXMLElement object. Then, we convert the SimpleXMLElement object to a JSON string using the json_encode() function. Finally, we convert the JSON string to an associative array named $dataArray using the json_decode() function with the second parameter set to true .

The array_merge() function in PHP allows you to merge two or more arrays into a single array. This is useful when you need to combine the elements of multiple arrays. Here’s an example:

In the above example, we have two arrays $fruits1 and $fruits2 that contain the names of fruits. By using the array_merge() function, we merge the elements of both arrays into a single array named $mergedFruits .

To retrieve the last element of an array in PHP, you can use the end() function. This function returns the value of the last element in the array without modifying the internal array pointer. Here’s an example:

In the above example, we have an array $fruits that contains the names of fruits. By using the end() function, we retrieve the last element of the array and store it in the variable $lastFruit .

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To retrieve the first element of an array in PHP, you can use the reset() function. This function returns the value of the first element in the array and resets the internal array pointer to the first element. Here’s an example:

In the above example, we have an array $fruits that contains the names of fruits. By using the reset() function, we retrieve the first element of the array and store it in the variable $firstFruit .

Arrays are commonly used for data manipulation in PHP. They provide a convenient way to store, access, and modify data. Let’s consider a use case where we have a list of students and their grades. We can use arrays to store this data and perform operations on it.

In the above example, we have an array $students that contains the names and grades of three students. Each student is represented as an associative array with “name” and “grade” as keys.

To access individual elements, you can use the corresponding keys:

You can also perform operations on the data, such as calculating the average grade:

In this example, we calculate the total grade of all students by iterating over the array using a foreach loop. We then divide the total by the number of students to calculate the average grade.

Arrays can also be used for data validation in PHP. When processing user input, it’s important to validate and sanitize the data to ensure its integrity and security. Let’s consider a use case where we have a form submission with multiple fields. We can use arrays to store and validate the submitted data.

In this example, we retrieve the values of the submitted form fields using the $_POST superglobal. We then perform validation checks on each field and store any validation errors in an array named $errors .

If the $errors array is empty, it means that the data is valid, and we can proceed with processing it. Otherwise, we display the validation errors to the user.

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When working with arrays in PHP, it’s important to follow naming conventions to improve code readability and maintainability. Here are a few best practices for naming arrays:

– Use descriptive names: Choose names that accurately describe the purpose or content of the array. For example, instead of using generic names like $data or $array , use names like $fruits or $studentGrades . – Use plural nouns: Since arrays typically store multiple values, it’s good practice to use plural nouns for array names. For example, use $fruits instead of $fruit . – Avoid abbreviations: Try to avoid unnecessary abbreviations in array names. Use full words or descriptive phrases to make the code more understandable. – Be consistent: Follow a consistent naming convention throughout your codebase to make it easier to understand and maintain.

When working with arrays in PHP, it’s important to consider the size limitations and memory usage associated with large arrays. Storing a large amount of data in memory can have performance implications and may cause memory exhaustion errors. Here are a few best practices for handling large arrays:

– Consider using pagination or lazy loading: If you’re dealing with a large dataset, it’s often more efficient to load and process the data in smaller chunks instead of loading the entire dataset into memory at once. Consider using pagination or lazy loading techniques to handle large arrays. – Use generators or iterators: PHP provides generators and iterators, which are memory-efficient ways to process large datasets. These constructs allow you to iterate over a dataset without loading the entire dataset into memory. – Optimize memory usage: Avoid unnecessary duplication of data within arrays. If possible, store references or pointers to data instead of duplicating the data itself. Additionally, unset or remove elements from the array when they are no longer needed to free up memory.

Arrays are widely used in data analysis to store and manipulate large datasets. Let’s consider a real-world example where we have a dataset of sales transactions. We can use arrays to store and analyze the data.

In the above example, we have an array $sales that contains sales transactions data. Each transaction is represented as an associative array with “product”, “quantity”, and “price” as keys.

We can perform various calculations on the data, such as calculating the total revenue:

In this example, we iterate over each transaction in the array using a foreach loop and calculate the revenue by multiplying the quantity with the price. The total revenue is stored in the variable $totalRevenue .

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Arrays are commonly used for handling user input in PHP applications. When working with forms, checkboxes, or multiple select inputs, the submitted data is often structured as an array. Let’s consider a real-world example where we have a form with multiple checkboxes. We can use arrays to handle the submitted data.

In the above example, we have a form with multiple checkboxes for selecting interests. The checkboxes have the same name attribute, followed by [] , which indicates that the values should be treated as an array when submitted.

In the PHP script that processes the form data ( process.php ), we can access the submitted interests as an array:

In this example, we retrieve the values of the submitted interests checkboxes using the $_POST superglobal. The values are stored in an array named $selectedInterests . We can then iterate over the array using a foreach loop and perform operations on each selected interest.

When working with arrays in PHP, it’s important to be mindful of memory usage, especially when dealing with large datasets. Storing a large amount of data in memory can have performance implications and may lead to memory exhaustion errors. Here are a few considerations to optimize memory usage:

– Use unset() to free memory: When you no longer need certain elements or entire arrays, use the unset() function to free up memory. This is particularly useful when working with large datasets and processing data in chunks. – Avoid unnecessary duplication: Be mindful of duplicating data within arrays. If possible, store references or pointers to data instead of duplicating the data itself. This can significantly reduce memory usage, especially when working with large arrays or nested data structures. – Use generators or iterators: PHP provides generators and iterators, which are memory-efficient ways to process large datasets. These constructs allow you to iterate over a dataset without loading the entire dataset into memory at once.

By optimizing memory usage, you can improve the performance and scalability of your PHP applications, particularly when dealing with large arrays or datasets.

When working with arrays in PHP, the performance of array operations can become a concern, especially when dealing with large datasets or performing computationally intensive tasks. Here are a few considerations to optimize processing time:

– Use array functions: PHP provides a wide range of built-in array functions that are optimized for performance. These functions are implemented in C and often outperform equivalent user-defined functions. – Avoid unnecessary operations: Be mindful of unnecessary array operations that can impact performance. For example, avoid repeatedly calling functions like count() inside loops when the array size remains constant. – Leverage native language constructs: PHP provides powerful language constructs like foreach loops and array iteration methods ( array_map() , array_filter() , etc.) that are optimized for performance. Leverage these constructs to minimize the overhead of looping and iteration.

By optimizing processing time, you can ensure that your PHP applications perform efficiently, particularly when working with large arrays or performing complex operations.

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Nested loops in PHP allow you to iterate over arrays within arrays, creating a multidimensional loop structure. This is useful when you need to perform operations on each element of a multidimensional array. Here’s an example:

In this example, we have a multidimensional array $matrix that represents a matrix of numbers. We use two nested foreach loops to iterate over each row and each element within the rows. The value of each element is then printed.

Nested loops are a powerful technique for working with multidimensional arrays, allowing you to perform operations on each element or combination of elements.

In PHP, you can dynamically create arrays by using loops, conditionals, or other logic to determine the array elements. This allows you to generate arrays based on specific requirements or dynamically changing data. Here’s an example:

By dynamically creating arrays, you can generate data structures that adapt to specific conditions or changing requirements.

Here’s a code snippet that demonstrates some basic array operations in PHP:

This code snippet demonstrates various array operations, such as accessing elements using indices, adding and modifying elements, removing elements using unset() , counting elements using count() , checking if an element exists using in_array() , and printing the array using print_r() .

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Here’s a code snippet that demonstrates the usage of multidimensional arrays in PHP:

This code snippet defines a multidimensional array $matrix that represents a matrix of numbers. It demonstrates how to access individual elements using indices ( $matrix[1][2] ) and how to iterate over each element using nested foreach loops.

Here’s a code snippet that demonstrates the usage of array search methods in PHP:

This code snippet shows how to search for a value within an array using array_search() and how to filter an array based on a condition using array_filter() . It demonstrates how to handle cases where the value is found or not found, and how to use a custom callback function with array_filter() .

Here’s a code snippet that demonstrates various array conversion techniques in PHP:

This code snippet demonstrates how to convert an array to a string using implode() , how to convert an array to an object using type casting, how to convert an array to JSON using json_encode() , and how to convert from JSON to an array using json_decode() .

Related Article: How to Delete An Element From An Array In PHP

Here’s a code snippet that demonstrates the usage of various array manipulation functions in PHP:

This code snippet demonstrates various array manipulation functions, such as sorting using sort() and rsort() , reversing using array_reverse() , shuffling using shuffle() , slicing using array_slice() , and merging using array_merge() . It shows how these functions can be used to modify and manipulate arrays in different ways.

When working with arrays in PHP, it’s important to be aware of common mistakes that can lead to errors or unexpected behavior. Here are a few common mistakes to avoid:

– Using undefined indices: When accessing elements using indices, make sure the indices exist. Accessing an undefined index will result in a notice or warning, and may lead to unexpected behavior. – Forgetting to initialize arrays: Before using an array, make sure to initialize it. Trying to modify or access elements of an uninitialized array will result in an error. – Overwriting array values unintentionally: Be careful when assigning values to array elements. Assigning a new value to an existing index will overwrite the previous value, potentially causing data loss or unexpected behavior. – Forgetting to unset or remove elements: If an element is no longer needed, make sure to unset or remove it from the array. Failing to do so can lead to unnecessary memory usage and potential bugs.

By avoiding these common mistakes, you can write more reliable and error-free code when working with arrays in PHP.

When working with arrays in PHP, debugging can be a valuable tool for identifying and resolving issues. Here are a few tips for debugging array-related problems:

– Use print_r() or var_dump() : These functions are useful for printing the contents and structure of an array, allowing you to inspect its elements and verify their values. – Check for undefined indices: If you encounter an “undefined index” notice or warning, use isset() or array_key_exists() to check if the index exists before accessing it. – Use error reporting: Enable error reporting in your PHP configuration or use the error_reporting() function to display errors and warnings. This can help identify issues related to arrays, such as undefined variables or incorrect array operations. – Step through code with a debugger: If you’re using an integrated development environment (IDE), take advantage of its debugging capabilities. Set breakpoints and step through your code to examine the state of arrays at different points.

By using these debugging techniques, you can identify and resolve array-related issues more effectively, leading to more robust and error-free code.

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php assignment from array

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PHP list(): Assign Values ​​from An Array To A Set Of Variables

The list() function in PHP is used to assign values to a list of variables in a single operation. It works only on numerical arrays and assumes that the numerical indices start at 0.

Here's a tutorial on how to use the list() function:

Step 1: Create an Indexed Array

First, you need to create an array. An array is a special variable that allows you to store multiple values in a single variable.

Step 2: Use the list() function

You can use the list() function to assign the values of the array to variables:

Step 3: Check the Result

You can now use these variables in your code. For example:

Note: The list() function is not used as much in newer versions of PHP (from PHP 7.1 onwards) because you can now use the shorthand array destructuring syntax, which works in exactly the same way:

This code does the same thing as the list() function in the previous example. It assigns the values of the array to the variables $fruit1 , $fruit2 , and $fruit3 .

That's it! This is a basic tutorial on how to use the list() function in PHP. It's a handy function when you need to assign the values of an array to a list of variables.

How to Use list() in PHP to Assign Array Values to Variables:

  • Description: list() is used to assign values from an array to individual variables in one operation.
  • Example Code: $coordinates = [10, 20, 30]; list($x, $y, $z) = $coordinates; echo "X: $x, Y: $y, Z: $z"; // Outputs: X: 10, Y: 20, Z: 30

Destructuring Arrays with list() in PHP:

  • Description: list() facilitates array destructuring, allowing easy assignment of values to variables.
  • Example Code: $person = ['John', 25, 'New York']; list($name, $age, $city) = $person; echo "Name: $name, Age: $age, City: $city"; // Outputs: Name: John, Age: 25, City: New York

PHP list() with Indexed Arrays:

  • Description: list() works seamlessly with indexed arrays, assigning values based on the order of elements.
  • Example Code: $colors = ['Red', 'Green', 'Blue']; list($first, $second, $third) = $colors; echo "First: $first, Second: $second, Third: $third"; // Outputs: First: Red, Second: Green, Third: Blue

Using list() with Associative Arrays in PHP:

  • Description: list() can also be used with associative arrays, assigning values based on the key names.
  • Example Code: $person = ['name' => 'Alice', 'age' => 30, 'city' => 'London']; list('name' => $name, 'age' => $age, 'city' => $city) = $person; echo "Name: $name, Age: $age, City: $city"; // Outputs: Name: Alice, Age: 30, City: London

PHP list() vs Individual Variable Assignment:

  • Description: list() provides a concise way to assign multiple values from an array in a single line.
  • Example Code: $coordinates = [5, 10, 15]; // Using list() list($x, $y, $z) = $coordinates; echo "X: $x, Y: $y, Z: $z"; // Individual variable assignment $x = $coordinates[0]; $y = $coordinates[1]; $z = $coordinates[2]; echo "X: $x, Y: $y, Z: $z"; // Outputs are the same: X: 5, Y: 10, Z: 15

Unpacking Array Values with list() in PHP:

  • Description: list() can be used to quickly unpack array values into variables, enhancing code readability.
  • Example Code: $point = [25, 30, 40]; list($x, $y, $z) = $point; echo "X: $x, Y: $y, Z: $z"; // Outputs: X: 25, Y: 30, Z: 40

Advanced Usage of list() in PHP:

  • Description: list() can be used in more advanced scenarios, such as nested arrays or function returns.
  • Example Code: $data = [ 'person' => ['Alice', 25, 'London'], 'scores' => [90, 85, 92] ]; list('person' => list($name, $age, $city), 'scores' => list($math, $english, $science)) = $data; echo "Name: $name, Age: $age, City: $city, Math: $math, English: $english, Science: $science"; // Outputs: Name: Alice, Age: 25, City: London, Math: 90, English: 85, Science: 92

PHP list() for Skipping Unwanted Array Elements:

  • Description: list() allows skipping unwanted elements when assigning values, improving flexibility.
  • Example Code: $coordinates = [10, 20, 30, 40]; list(, $y, , $z) = $coordinates; echo "Y: $y, Z: $z"; // Outputs: Y: 20, Z: 40

Handling Mismatched Variable Counts with list() in PHP:

  • Description: list() handles mismatched variable counts gracefully, assigning values up to the available variables.
  • Example Code: $values = [1, 2, 3]; list($a, $b, $c, $d) = $values; echo "A: $a, B: $b, C: $c, D: $d"; // Outputs: A: 1, B: 2, C: 3, D:

list() Function in PHP and Its Alternatives:

  • Description: list() is a convenient way for array value assignment. Alternatives include individual variable assignments and array destructuring.
  • Example Code: $colors = ['Red', 'Green', 'Blue']; // Using list() list($first, $second, $third) = $colors; echo "First: $first, Second: $second, Third: $third"; // Individual variable assignment $first = $colors[0]; $second = $colors[1]; $third = $colors[2]; echo "First: $first, Second: $second, Third: $third"; // Outputs are the same: First: Red, Second: Green, Third: Blue

Common Mistakes and Pitfalls with PHP list() :

  • Description: Common mistakes include mismatched variable counts and attempting to use list() with non-array values.
  • Example Code: $data = [10, 20, 30]; // Mistake: Mismatched variable count list($x, $y) = $data; // Mistake: Using list() with non-array value list($value) = 42;

Tips for Efficient Variable Assignment Using list() in PHP:

  • Description: Use list() when dealing with multiple values from an array, enhancing code readability.
  • Example Code: $point = [15, 25, 30]; // Less efficient alternative $x = $point[0]; $y = $point[1]; $z = $point[2]; // More efficient with list() list($x, $y, $z) = $point;

Matt Mickiewicz

Using PHP Arrays: A Guide for Beginners

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Using PHP Arrays: A Guide for Beginners

Introduction to PHP Arrays

Basic concepts: what is an array, basic syntax: creating and accessing arrays, types of indexes in php arrays, popular questions about php arrays, appending elements to a php array.

In this article, we’ll cover the basics of PHP arrays along with some advanced concepts. We’ll start by introducing you to what an array is, before moving on to the basic syntax of arrays and the different types of indexes available.

PHP arrays are powerful data structures that allow developers to store and manipulate collections of values. An array is a variable that can hold multiple values, each identified by a unique key or index value.

Arrays in PHP can be used in many ways, such as storing user input, accessing file system directories and files, managing database results and much more. With built-in functions for sorting, searching, filtering and transforming arrays, working with them in PHP is easy.

An array is a collection of variables grouped under one name. It allows the developer to store multiple pieces of data (values) under one variable name instead of creating individual variables for each element.

The array() function accepts any number of comma-separated values. The values contained within an array can be of different data types such as integers, strings, Booleans or even other arrays.

To create an array in PHP, we use the following syntax:

Here’s an example of creating a simple indexed array containing three elements (numbers):

We can access individual elements in an indexed array by their position (or index) within the array. In PHP (and many other programming languages) arrays are zero-indexed, meaning that the first element starts at position zero and not one. To access a particular element by its index, we simply reference it like this:

In this example, we’re accessing the first element of $num_array by its index, which is zero.

PHP arrays can have different types of indexes. The most commonly used are indexed and associative arrays.

Indexed arrays

An indexed array uses numeric indices to access and store values in an array. Here’s an example:

The above code creates an indexed (numerically keyed) array containing three elements/colors. We can easily access each element/color using its corresponding index within square brackets as shown above.

Associative arrays

On the other hand, associative arrays use named keys/indices instead of numerical ones to store data. This makes it easier for developers to retrieve values according to the keys they set.

Here’s an example:

In the code above, we have an associative array with three key–value pairs. We can access data from this array by using the corresponding key name.

Here are ten of the most popular questions beginning web developers ask about PHP arrays and their answers.

How do I add elements to an existing PHP Array?

You can add elements to an existing PHP indexed or associative array using the array_push() or [] (square bracket) notation. Using array_push() , we can append one or more values to the end of an array.

In this code snippet, we have added two new elements ( banana and grape ) to the existing $fruits array using the array_push() .

Alternatively, you can use square brackets notation by assigning a value to a new index position in an indexed array or setting a new key–value pair for associative arrays.

For example, to add element to indexed arrays, $num_array[] = 67; will add the value 67 at the end of the $num_array .

As an example of adding an element to an associative array, $user_data['country'] = 'United States'; will add a new key–value pair to the $user_data array.

How do I remove elements from an existing PHP Array?

You can remove elements from an existing PHP array using the unset() function or the array_splice() function. Using the unset() function, you can remove a specific element of an indexed or associative PHP array by specifying its index or key respectively.

Here’s an example code snippet:

In this example, we’ve removed the third element ( banana ) of the $fruits array using the unset() function.

Alternatively, you can use the array_splice() function to remove a range of elements from an indexed array. To remove a key–value pair from an associative array, you can also use the unset() function by specifying the key that you want to remove.

In this code snippet, we have removed the 'country' key–value pair from the $user_data associative array using the unset() function.

How do I check if a value exists in an array in PHP?

You can check if a value exists in an array in PHP by using the in_array() function. The in_array() function searches for a given value in an array, and returns true if the value is found and false otherwise.

In this example, we’ve used the in_array() function to check if the value apple exists in the $fruits array. Since apple is present in the array, the condition evaluates to true and the message Apple is in the fruits array is outputted. If apple was not present in the array, the message Apple is not in the fruits array would have been outputted instead. The in_array() function is case-sensitive, so apple and Apple would be treated as two different values. If you want a case-insensitive search, you can use the array_search() function instead.

How do I remove elements from an existing PHP array?

You can remove elements from an existing PHP array using the unset() function or the array_splice() function. Using the unset() function, you can remove a specific element of an indexed or associative PHP array by specifying its index or key respectively. Alternatively, you can use the array_splice() function to remove a range of elements from an indexed array.

To remove a range of elements from an indexed array using the array_splice() function, you need to specify the starting index and the number of elements to remove.

In this example, we’ve removed the elements at indices 1 and 2 (i.e., orange and banana ) from the $fruits array using the array_splice() function.

To remove a key–value pair from an associative array using the unset() function, you can provide the key of the element you want to remove as the argument.

Here is an example code snippet:

This code snippet shows how to remove the city key–value pair from the user_data associative array using the unset() function.

How do you loop through a PHP array?

To loop through a PHP array, you can use a foreach loop like this:

In the above code, $array is the name of the array you want to loop through. $key and $value are variables that will hold the key and value of the current element of the array, respectively. You can then use these variables to perform some action for each element of the array.

How do you sort a PHP array?

Sorting is a common operation when working with arrays in PHP. The following are some of the functions you can use to sort arrays:

  • sort() : sorts the values of an array in ascending order
  • rsort() : sorts the values of an array in descending order
  • asort() : sorts an associative array in ascending order, according to the value
  • arsort() : sorts an associative array in descending order, according to the value
  • ksort() : sorts an associative array in ascending order, according to the key
  • krsort() : sorts an associative array in descending order, according to the key

How to create a multidimensional array in PHP?

To create a multidimensional array in PHP, you simply create an array of arrays.

In the above example, we’ve created a multidimensional array with three arrays, each containing two elements.

You can append elements to a PHP array using the [] operator or the array_push() function.

Using the [] operator

Here’s an example of appending elements to an array using the [] operator:

In the code above, we first create an array called $countries with three elements. We then append two more elements to the array using the array[] operator.

Using the array_push() function

Here’s an example of appending elements to an array using the array_push() function:

In the above code, we first create an array called $countries with three elements. We then append two more elements to the array using array_push .

This article has covered some of the most frequently asked questions related to PHP arrays.

Arrays are an essential data structure in PHP, allowing developers to store and manipulate collections of data easily. We’ve learned how to create, add elements to, remove elements from, and loop through arrays in PHP. By using multidimensional arrays, we can organize data into multiple dimensions or layers, and a vast range of built-in functions are available to manipulate and traverse arrays.

Remember, PHP arrays don’t have to be indexed numerically: they can also be associated with keys. We can use these keys to associate values with specific pieces of data, allowing us to retrieve and manipulate specific items easily.

Matt is the co-founder of SitePoint, 99designs and Flippa. He lives in Vancouver, Canada.

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PHP Array – How to Use Arrays in Your PHP Projects

Okoro Emmanuel Nzube

An array is a special variable that we use to store or hold more than one value in a single variable without having to create more variables to store those values.

To create an array in PHP, we use the array function array( ) .

By default, an array of any variable starts with the 0 index. So whenever you want to call the first value of an array you start with 0 then the next is 1 ...and so on.

There are different types of arrays in PHP. They are:

  • Numeric/Indexed Arrays
  • Associative Arrays
  • Multidimensional Arrays

Let's look at how each one works in more detail.

What are Numerical or Indexed Arrays?

A numerical array is a type of array which can store strings, numbers, and objects. Here's an example of a numeric array:

From the code above I have a variable of   $cars which stores an array of 5 elements. The var_dump($cars) keyword above will show us the total number of elements we have in the array, the index number of each array, and also the length of each element in the array.

You can also chose to use the echo( ) keyword, but in my case I prefer to use var_dump( ) because it gives a more detailed explanation of the results we get.

localhost_CODE_Arrays_arrays.php---Google-Chrome-6_15_2022-8_44_07-PM

You can also choose to display only one element/item of an array in the web browser by doing this:

The code above follows the same pattern as our definition of an array, which states that it counts from zero. We want to display the element with the index of 4 . Counting from 0 to 4 , we can see that 88 falls under index 4 , indicating that 88 is the number we're seeking and that will be displayed to the browser.

localhost_CODE_Arrays_arrays.php---Google-Chrome-6_17_2022-8_17_58-PM

What are Associative Arrays?

An associative array is a type of array where the key has its own value. In an associative array, we make use of key and value .

Key s are descriptive captions of the array element used to access the value of the array. And value is the value assigned to the array element.

There are situations where you shouldn't use the numeric/indexed array, such as:

  • When you want to store the age of different students along with their names.
  • When you want to record the salaries of your employees.
  • When you want to store the score of a student in different subjects

and so on.  

Suppose we want to assign ages to a group of high school students with their names.

We can use the Associative array method to get it done. For example:

The code above is an example of an associative array. The key s of the array are scott_Mcall , Stalenski , Lydia , Allision , and we used them to assign the age to each student. The value s of the array are 17 , 18 , 16 , and 17 .

What are Multidimensional Arrays?

You can think of a multidimensional array as an array of arrays. This means that every element in the array holds a sub-array within it. In general, multidimensional arrays allow you to store multiple arrays in a single variable.

Suppose we want to store the Names, Registration Numbers, and Emails of some of the staff working in a particular company. We can use multidimensional arrays to archive this.

For example:

Remember, an array starts counting from index 0 . The code above is an example of a multidimensional array because it contains more than one array (an array of arrays) with one single variable of $staff .

The echo $staff [2] [‘Email’] displays the email of the staff that falls into the index of 2 . In our case it will display [email protected] .

If I want to access the Email of the staff in the first array, we'll do the following:

echo $staff [0] ['Email'];

Using the method above, you can access and display any information in the array from the code above.

At this point you should be able to use the three different types of arrays when working on a PHP project.

Thank you for reading.

Have fun coding!

Hello, I go by the alias "Derek". I'm proficient in a wide range of technical skills, which I gained and continued to to hone through self-education.

If you read this far, thank the author to show them you care. Say Thanks

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Home » PHP Tutorial » PHP Assignment Operators

PHP Assignment Operators

Summary : in this tutorial, you will learn about the most commonly used PHP assignment operators.

Introduction to the PHP assignment operator

PHP uses the = to represent the assignment operator. The following shows the syntax of the assignment operator:

On the left side of the assignment operator ( = ) is a variable to which you want to assign a value. And on the right side of the assignment operator ( = ) is a value or an expression.

When evaluating the assignment operator ( = ), PHP evaluates the expression on the right side first and assigns the result to the variable on the left side. For example:

In this example, we assigned 10 to $x, 20 to $y, and the sum of $x and $y to $total.

The assignment expression returns a value assigned, which is the result of the expression in this case:

It means that you can use multiple assignment operators in a single statement like this:

In this case, PHP evaluates the right-most expression first:

The variable $y is 20 .

The assignment expression $y = 20 returns 20 so PHP assigns 20 to $x . After the assignments, both $x and $y equal 20.

Arithmetic assignment operators

Sometimes, you want to increase a variable by a specific value. For example:

How it works.

  • First, $counter is set to 1 .
  • Then, increase the $counter by 1 and assign the result to the $counter .

After the assignments, the value of $counter is 2 .

PHP provides the arithmetic assignment operator += that can do the same but with a shorter code. For example:

The expression $counter += 1 is equivalent to the expression $counter = $counter + 1 .

Besides the += operator, PHP provides other arithmetic assignment operators. The following table illustrates all the arithmetic assignment operators:

Concatenation assignment operator

PHP uses the concatenation operator (.) to concatenate two strings. For example:

By using the concatenation assignment operator you can concatenate two strings and assigns the result string to a variable. For example:

  • Use PHP assignment operator ( = ) to assign a value to a variable. The assignment expression returns the value assigned.
  • Use arithmetic assignment operators to carry arithmetic operations and assign at the same time.
  • Use concatenation assignment operator ( .= )to concatenate strings and assign the result to a variable in a single statement.

In this lesson, we'll learn how we can store multiple values in a single variables.

Sometimes, we need to keep a list of things in order. It's like a shopping list where you have the first item to buy, the second item, the third item, and so on. We might need this kind of list in computer programming, too, for things like a list of users on a website, a catalog of products for sale, or even parts of a webpage.

There exists a special data structure named Array , to store ordered collections. In PHP, an array is a special variable which can hold more than one value at a time. It is a collection of elements of similar or different data types.

There are three types of arrays that you can create:

  • Indexed arrays : An array with a numeric index where values are stored linearly.
  • Associative arrays : An array where each ID key is associated with a value. The key can be any string or an integer.
  • Multidimensional arrays : These are arrays that contain one or more arrays within them.

Let's go through each one.

Declaring an array

There are two syntaxes for creating an array in PHP. You can use the array() function or set the variable value to a pair of square brackets. Either solution is valid. Here's an example:

To create an array with some initial items, you could do something like this:

In an array, we start counting from zero. This means the first item is 0 , the second item is 1 , and so on. We refer to this type of array as an indexed array. An indexed array is a type of array in PHP where each element is stored with an index that is usually an integer starting from 0 .

Definition: element

The word "element" refers to a key-value pair in an array.

If you want to get a specific item from the array, you use its number. For example:

You can change an item in the array just by assigning a new value to it. Like this:

And if you want to add a new item to the array, you can do it like this:

Alternatively, you can leave the square brackets empty. PHP automatically adds the value as the last item in the array.

So in PHP, an array is just a way to keep a list of items in a single variable. You can get items, change them, and add new ones all you want!

Outputting Arrays

PHP offers two functions for viewing the contents of an array. The first is the var_dump() function. Take the following:

This outputs the following:

Alternatively, you can use the print_r() function, which accepts the array as a value.

This function outputs the following:

The difference between the var_dump() function and print_r() function is that the var_dump() function outputs the values along with their data types. Whereas the print_r() function only outputs the values. In some cases, you may not be interested in viewing the data types. For less clutter, the print_r() function can be useful for readability.

Associative Arrays

An associative array in PHP is a type of array that uses keys and values to store data. Unlike an indexed array which uses numbers as indexes, an associative array allows you to use more meaningful keys (like strings), which can make your code easier to understand and work with.

Think of an associative array as a collection of items with labels on them. For instance, you could have a box of items where each item has a label that describes what's inside. In PHP, the label would be the key, and the item would be the value.

Here's an example of an associative array that stores the colors of fruits:

In this example, the names of the fruits ( "Apple" , "Banana" , "Grape" ) are the keys, and the colors ( "Red" , "Yellow" , "Purple" ) are the values.

If you want to know what color the banana is, you would "look up" the value using its key like this:

Inside the square brackets, you would type the key name instead of a numeric index.

You can change the color of the banana or add a new fruit to the array like this:

Indexed arrays vs Associative arrays

Both types of arrays have their advantages. Choosing between indexed and associative arrays often comes down to the nature of the data you're working with and what you need to do with it.

  • Meaningful Keys : When you want to store data that's easier to read and understand, associative arrays are very helpful because you can assign meaningful keys to values.
  • Searching by Key : If you frequently need to find values based on their names (keys), associative arrays make this process simple and quick.
  • Working with Unique Data : Associative arrays ensure that keys are unique, which is useful when dealing with data where certain values must not be duplicated, like usernames or product IDs.
  • Mapping/Relating Data : If your data has a natural key-value relationship (like a product and its price or a student and their grade), an associative array is a more intuitive choice.

Indexed Arrays

  • Simplicity : Indexed arrays are simpler as you only need to think about the values and their order, not their names.
  • Ordered Data : When the order of data matters (such as a timeline of events, a list of instructions), indexed arrays are a good fit because each element automatically has an order based on its index.
  • Unknown size : You may not always know how many items you need to store, so an indexed array can be useful in these scenarios.

Multidimensional arrays

A multidimensional array in PHP is an array that contains one or more arrays within it. This allows you to store data in a more complex and structured manner, which can be particularly useful when you need to manage groups of related data.

To make it easier to understand, let's imagine a simple shelf. This shelf can contain several books. In PHP, we can represent this as an array:

Now, imagine we have a bookcase with multiple shelves, and each shelf contains several books. We can represent this situation using a multidimensional array:

In this example, the "top" , "middle" , and "bottom" are arrays themselves, each containing several books. This is a two-dimensional array.

We can access any book from any shelf by using two indices. The first index gets us to the shelf, and the second index gets us to the book:

We can also modify or add new books to any shelf:

So, a multidimensional array in PHP is just an array that contains other arrays, which can be very useful for organizing and storing complex data structures.

Array Typecasting

Mon-array values can be type casted into arrays using (array) . Depending on the data type of the original value, the resulting array may look different.

Arrays are a special case. They can be converted, but PHP does throw a warning during this process. It's not able to completely convert an array to a string. In most cases, the value is inserted as an item in the array.

For null values, an empty array is returned. Here are some examples:

Here are some code examples:

Key Takeaways

  • To make a new array, you can either use array() or [] .
  • In an indexed array, counting starts from 0 , not 1 .
  • If you want to get to a specific item in the array, put the item's number (also known as its index) inside square brackets like this: $arrayName[indexNumber] .
  • Associative arrays use named keys instead of numeric indexes. You can reference a specific item by its key name.
  • Multidimensional arrays are nested array structures. There's no limit as to how many nested arrays you can have.
  • You can cast non-array values into arrays by using (array) .

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PHP Tutorial

Php advanced, mysql database, php examples, php reference, php associative arrays.

Associative arrays are arrays that use named keys that you assign to them.

Access Associative Arrays

To access an array item you can refer to the key name.

Display the model of the car:

Change Value

To change the value of an array item, use the key name:

Change the year item:

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Loop Through an Associative Array

To loop through and print all the values of an associative array, you could use a foreach loop, like this:

Display all array items, keys and values:

For a complete reference of all array functions, go to our complete PHP Array Reference .

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Create an associative array containing the age of Peter, Ben and Joe.

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Move all zeros to front of array

Given an array arr[] of integers, the task is to move all the zeros to the front of the array while preserving the order of non-zero elements. Modify the given array inplace.

Input: arr[] = {1, 0, 20, 4, 3, 0, 0, 5} Output: 0 0 0 1 20 4 3 5 Input: arr[] = {1, 0, 2, 0, 3, 0} Output: 0 0 0 1 2 3

Move all zeros to front of array using Linear Space O(N):

We can solve this problem by taking another array to store the non-zero numbers of the input array. Also, count the number of zeros present in the input array. Then, we can start filling the input array from the beginning with zeros and then fill the remaining array with non-zero numbers from the temp array.

Step-by-step algorithm:

  • Initialize an empty list, say temp .
  • Traverse through the array arr[] and insert/push all the non-zero elements into the temp list.
  • Count the number of the zeros and store in count variable in the given array arr[] .
  • Modify the given array. Place count number of zeros in the beginning of the array arr[] .
  • Now replace the remaining elements of the array with the elements stored in temp list.

Below is the implementation of the algorithm:

Time Complexity: O(n), where n is number of elements in input array. Auxiliary Space: O(k), where k is number of non-zero elements

Move all zeros to front of array using Constant Space O(1):

We can solve the problem by maintaining a pointer to the last zero of the array, say end and then start iterating from the pointer to the beginning. If at any index i we find a non-zero value, we swap the arr[i] with arr[end] and decrement the end by 1. Here end always points to last zero in the array arr[].
  • Traverse the array arr[] from the end and find the index of last zero in the arr[], store it in a variable say end.
  • Now, start traversing from end-1 to 0.
  • While traversing, if the element in the array arr[] is not equal to zero, swap it with arr[end].
  • After swapping, decrement the value of end.
  • Repeat the above steps till we have traversed all the elements from end to 0.

Time Complexity: O(n), n is number of elements in the input array. Auxiliary Space: O(1)

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array_column

(PHP 5 >= 5.5.0, PHP 7, PHP 8)

array_column — Return the values from a single column in the input array

Description

array_column() returns the values from a single column of the array , identified by the column_key . Optionally, an index_key may be provided to index the values in the returned array by the values from the index_key column of the input array.

A multi-dimensional array or an array of objects from which to pull a column of values from. If an array of objects is provided, then public properties can be directly pulled. In order for protected or private properties to be pulled, the class must implement both the __get() and __isset() magic methods.

The column of values to return. This value may be an integer key of the column you wish to retrieve, or it may be a string key name for an associative array or property name. It may also be null to return complete arrays or objects (this is useful together with index_key to reindex the array).

The column to use as the index/keys for the returned array. This value may be the integer key of the column, or it may be the string key name. The value is cast as usual for array keys (however, prior to PHP 8.0.0, objects supporting conversion to string were also allowed).

Return Values

Returns an array of values representing a single column from the input array.

Example #1 Get the column of first names from a recordset

The above example will output:

Example #2 Get the column of last names from a recordset, indexed by the "id" column

Example #3 Get the column of usernames from the public "username" property of an object

Example #4 Get the column of names from the private "name" property of an object using the magic __get() method.

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COMMENTS

  1. PHP Assign array to variables

    As for using explode() with list() or array destructuring, if you are not guaranteed a certain number of elements, it is best practice to declare the 3rd parameter of explode() to limit the number of generated elements. This will not force the production of so many elements; rather it will merely tell php to stop exploding when that number of elements is achieved.

  2. How can I assign an array to another variable in php?

    PHP - Assign variable and use it to assign value to array all in one step Hot Network Questions Looked at a different rolling (3d6, 3d6, average) for D&D characters in AnyDice and the result didn't come out as expected.

  3. PHP: Arrays

    Arrays. An array in PHP is actually an ordered map. A map is a type that associates values to keys. This type is optimized for several different uses; it can be treated as an array, list (vector), hash table (an implementation of a map), dictionary, collection, stack, queue, and probably more. ... This is done by assigning values to the array ...

  4. PHP Arrays

    In PHP, there are three types of arrays: Indexed arrays - Arrays with a numeric index. Associative arrays - Arrays with named keys. Multidimensional arrays - Arrays containing one or more arrays.

  5. PHP: array

    PHP: array - Manual array is a function that creates an array from a list of variables. It can also be used to access the elements of an array by index or key. Learn how to use this function with examples and see how it differs from other array functions and types in PHP.

  6. PHP: Assignment

    In addition to the basic assignment operator, there are "combined operators" for all of the binary arithmetic, array union and string operators that allow you to use a value in an expression and then set its value to the result of that expression.For example:

  7. How to Work with PHP Arrays: a Complete Guide

    In PHP, you can add elements to an array by assigning a value to a specific index or by using the array_push() function. Here are a few examples: Here are a few examples: Adding an element using index assignment:

  8. PHP list(): Assign Values from An Array To A Set Of Variables

    Step 1: Create an Indexed Array. First, you need to create an array. An array is a special variable that allows you to store multiple values in a single variable. Step 2: Use the list() function. You can use the list() function to assign the values of the array to variables: Step 3: Check the Result.

  9. Using PHP Arrays: A Guide for Beginners

    Introduction to PHP Arrays. PHP arrays are powerful data structures that allow developers to store and manipulate collections of values. An array is a variable that can hold multiple values, each ...

  10. PHP Array

    An array is a special variable that we use to store or hold more than one value in a single variable without having to create more variables to store those values. To create an array in PHP, we use the array function array( ). By default, an array of any variable starts with the 0 index. So whenever you want to call the first value of an array ...

  11. PHP array

    PHP array definition. Arrays are collections of data. A variable can hold only one item at a time. Arrays can hold multiple items. Note: a PHP array is a collection which is used both as a list and a map. PHP has plenty of functions to modify, sort, merge, slice, shuffle the data inside the arrays.

  12. Learn PHP: Learn PHP Arrays Cheatsheet

    In PHP, associative arrays are map-like structures, where keys are associated with values. When we need to access a specific value, we can use the associated key to find it. In a PHP ordered array, the index locations are the keys. However, the PHP array type also allows us to assign meaningful keys to values.

  13. PHP Assignment Operators

    Use PHP assignment operator ( =) to assign a value to a variable. The assignment expression returns the value assigned. Use arithmetic assignment operators to carry arithmetic operations and assign at the same time. Use concatenation assignment operator ( .= )to concatenate strings and assign the result to a variable in a single statement.

  14. PHP: Array Functions

    count — Counts all elements in an array or in a Countable object. current — Return the current element in an array. each — Return the current key and value pair from an array and advance the array cursor. end — Set the internal pointer of an array to its last element. extract — Import variables into the current symbol table from an array.

  15. Arrays

    Arrays in PHP are data structures that store multiple values in a single variable. They can hold any type of values and be multi-dimensional. ... You can change an item in the array just by assigning a new value to it. Like this: $ fruits [2] = ' Pear '; // Now the array is: ("Apple", "Orange", "Pear")

  16. PHP Associative Arrays

    Well organized and easy to understand Web building tutorials with lots of examples of how to use HTML, CSS, JavaScript, SQL, Python, PHP, Bootstrap, Java, XML and more.

  17. Move all zeros to front of array

    Time Complexity: O(n), where n is number of elements in input array. Auxiliary Space: O(k), where k is number of non-zero elements Move all zeros to front of array using Constant Space O(1): We can solve the problem by maintaining a pointer to the last zero of the array, say end and then start iterating from the pointer to the beginning. If at any index i we find a non-zero value, we swap the ...

  18. PHP: Array

    The + operator returns the right-hand array appended to the left-hand array; for keys that exist in both arrays, the elements from the left-hand array will be used, and the matching elements from the right-hand array will be ignored.

  19. php

    I am going to assign another array to this array items.In fact doing a foreach loop and due to situation assign a new array to desired array item. Now i want turn it to this: Now i want turn it to this:

  20. PHP: array_column

    column_key. The column of values to return. This value may be an integer key of the column you wish to retrieve, or it may be a string key name for an associative array or property name. It may also be null to return complete arrays or objects (this is useful together with index_key to reindex the array). index_key.

  21. Parallel array assignment in PHP

    Parallel array assignment in PHP. Ask Question Asked 14 years, 2 months ago. Modified 4 years, 4 months ago. ... 23 Most languages make it easy to take an array like [1, 2, 3] and assign those values to variables a, b, and c with a single command. For example, in Perl you can do

  22. Assign data from a jason file to an array outside of fetch() for the

    Assign data from a jason file to an array outside of fetch() for the purpose of using user input to filter the jason file data. Ask Question Asked today. ... but which gave me problems in loading data: Why are the two arrays different? Is there any way to get an array of data like the ones in point 1 from fetch()?

  23. c

    Array Element Assignment [closed] Ask Question Asked today. Modified today. Viewed 45 times -2 Closed. This question needs details or clarity. It is not currently accepting answers. Want to improve this question? Add details and clarify the problem by editing this post. Closed 56 mins ago. This post ...