PHP preg_grep Function: Usage, Parameters, Return Value, and Example

preg_grep() returns an array of elements from the input array that match the given regular‑expression pattern.

Parameters

pattern : The regex pattern to search for (string).

input : The input array.

flags : Optional flag; if set to PREG_GREP_INVERT, the function returns elements that do not match the pattern.

Return value : An array indexed by the original keys of the input array.

Example 1:

<?php
// Return all elements containing a floating‑point number
$array = array(1, 2, 3.4, 53, 7.9);
$fl_array = preg_grep("/^(
    \d+)?\.\d+$/", $array);
print_r($fl_array);
?>

Output:

Array
(
    [2] => 3.4
    [4] => 7.9
)