What is foreach loop in php?

(PHP 4, PHP 5, PHP 7, PHP 8)

The foreach construct provides an easy way to iterate over arrays. foreach works only on arrays and objects, and will issue an error when you try to use it on a variable with a different data type or an uninitialized variable. There are two syntaxes:

foreach (iterable_expression as $value)
    statement
foreach (iterable_expression as $key => $value)
    statement

The first form traverses the iterable given by iterable_expression. On each iteration, the value of the current element is assigned to $value.

The second form will additionally assign the current element's key to the $key variable on each iteration.

Note that foreach does not modify the internal array pointer, which is used by functions such as current() and key().

It is possible to customize object iteration.

In order to be able to directly modify array elements within the loop precede $value with &. In that case the value will be assigned by reference.

$arr = array(1, 2, 3, 4);
foreach ($arr as &$value) {
    $value = $value * 2;
}
// $arr is now array(2, 4, 6, 8)
unset($value); // break the reference with the last element
?>

Warning

Reference of a $value and the last array element remain even after the foreach loop. It is recommended to destroy it by unset(). Otherwise you will experience the following behavior:

$arr = array(1, 2, 3, 4);
foreach ($arr as &$value) {
    $value = $value * 2;
}
// $arr is now array(2, 4, 6, 8)

// without an unset($value), $value is still a reference to the last item: $arr[3]

It is possible to iterate a constant array's value by reference:

foreach (array(1, 2, 3, 4) as &$value) {
    $value = $value * 2;
}
?>

Note:

foreach does not support the ability to suppress error messages using @.

Some more examples to demonstrate usage:

/* foreach example 1: value only */$a = array(1, 2, 3, 17);

foreach (

Unpacking nested arrays with list()

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

It is possible to iterate over an array of arrays and unpack the nested array into loop variables by providing a list() as the value.

For example:

$array = [
    [1, 2],
    [3, 4],
];

foreach (

The above example will output:

You can provide fewer elements in the list() than there are in the nested array, in which case the leftover array values will be ignored:

$array = [
    [1, 2],
    [3, 4],
];

foreach (

The above example will output:

A notice will be generated if there aren't enough array elements to fill the list():

$array = [
    [1, 2],
    [3, 4],
];

foreach (

The above example will output:

Notice: Undefined offset: 2 in example.php on line 7
A: 1; B: 2; C: 

Notice: Undefined offset: 2 in example.php on line 7
A: 3; B: 4; C: 

Sanusi Hassan ¶

4 days ago

destructure array elements

you can unpac nested array elements using the following

$array = [
    [1, 2],
    [3, 4],
];

foreach (

Okafor Chiagozie ¶

1 day ago

An easier way to unpack nested array elements

$array = [
    [1, 2],
    [3, 4],
];

foreach ($array as [$a, $b]) {
    echo "A: $a; B: $b\n";
}