PHP reset Function

last modified March 13, 2025

The PHP reset function rewinds array's internal pointer to the first element. It's useful when you need to start processing an array from the beginning.

Basic Definition

The reset function sets the internal pointer of an array to its first element. It returns the value of the first array element or false if the array is empty.

Syntax: reset(array &$array): mixed. The function takes an array by reference and returns its first element's value. It affects the array's internal pointer.

Basic reset Example

This demonstrates how to reset an array's internal pointer to its start.

basic_reset.php

<?php

$fruits = ['apple', 'banana', 'cherry'];

// Move pointer to second element
next($fruits);

// Reset to first element
$first = reset($fruits);

echo "First fruit: $first";

After moving the pointer with next, reset returns it to the first element. The function also returns the first element's value.

Getting First Element

Use reset to safely get an array's first element without knowing its key.

get_first_element.php

<?php

$colors = ['red' => '#FF0000', 'green' => '#00FF00', 'blue' => '#0000FF'];

$firstColor = reset($colors);

echo "First color code: $firstColor";

This retrieves the first value from an associative array without needing to know its key. reset is handy for arrays with unknown keys.

Empty Array Handling

reset returns false for empty arrays, which requires careful handling.

empty_array.php

<?php

$emptyArray = [];

$result = reset($emptyArray);

if ($result === false) {
    echo "Array is empty or first element is false";
} else {
    echo "First element: $result";
}

Since reset returns false for empty arrays, use strict comparison to distinguish from a false first element. This prevents bugs.

Combined with current

Compare reset with current to understand pointer position.

reset_vs_current.php

<?php

$numbers = [10, 20, 30];

next($numbers); // Move to second element
echo "Current: " . current($numbers) . "\n"; // 20

reset($numbers);
echo "After reset: " . current($numbers); // 10

This shows how reset changes the internal pointer position. current confirms the pointer moved back to the first element.

In Loop Processing

Use reset when you need to reprocess an array multiple times.

loop_processing.php

<?php

$data = ['A', 'B', 'C'];

// First processing
while ($value = current($data)) {
    echo "$value ";
    next($data);
}

reset($data); // Rewind for second processing

// Second processing
while ($value = current($data)) {
    echo strtolower($value) . " ";
    next($data);
}

After the first loop exhausts the array, reset allows processing again. This outputs "A B C a b c", demonstrating array reuse.

Best Practices

Pointer Awareness: Remember it affects array's internal pointer.
Empty Arrays: Always check return value for empty arrays.
Alternative: Consider array_key_first for PHP 7.3+.
Performance: Minimal overhead for small to medium arrays.

Source

PHP reset Documentation

This tutorial covered the PHP reset function with practical examples showing its usage for array pointer management.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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