How to create comma separated list from an array in PHP?

Creating a comma-separated list from an array in PHP is efficiently done using the built-in implode() function. This function joins array elements with a specified delimiter string.

Syntax

implode(separator, array)

Parameters

separator: The string to use as a delimiter between array elements (optional, defaults to empty string).

array: The array whose elements you want to join.

Basic Example

Here's a simple example of creating a comma-separated list from a numeric array ?

<?php
    $arr = array(100, 200, 300, 400, 500);
    echo "Original array: ";
    print_r($arr);
    echo "\nComma separated list: ";
    echo implode(', ', $arr);
?>

Original array: Array
(
    [0] => 100
    [1] => 200
    [2] => 300
    [3] => 400
    [4] => 500
)

Comma separated list: 100, 200, 300, 400, 500

Handling Whitespace in Array Elements

When array elements contain extra whitespace, you may want to trim them before creating the list ?

<?php
    $arr = array(" John ", "Jacob ", " Tom ", " Tim ");
    echo "Array with whitespaces:<br>";
    foreach($arr as $value) {
        echo "Value = '$value'<br>";
    }
    
    // Create comma-separated list with trimmed values
    $trimmed = array_map('trim', $arr);
    echo "\nComma separated list: ";
    echo implode(', ', $trimmed);
?>

Array with whitespaces:
Value = ' John '
Value = 'Jacob '
Value = ' Tom '
Value = ' Tim '

Comma separated list: John, Jacob, Tom, Tim

Different Separators

You can use any separator, not just commas ?

<?php
    $fruits = array("apple", "banana", "orange");
    
    echo "Comma separated: " . implode(', ', $fruits) . "<br>";
    echo "Pipe separated: " . implode(' | ', $fruits) . "<br>";
    echo "Dash separated: " . implode(' - ', $fruits) . "<br>";
?>

Comma separated: apple, banana, orange
Pipe separated: apple | banana | orange
Dash separated: apple - banana - orange

Conclusion

The implode() function is the most efficient way to create comma-separated lists from PHP arrays. Combine it with array_map('trim', $array) to handle whitespace issues in your data.