(PHP 4, PHP 5, PHP 7, PHP 8)
preg_grep — Return array entries that match the pattern
$pattern, array $array, int $flags = 0): array|false
   Returns the array consisting of the elements of the 
   array array that match the given
   pattern.
  
patternThe pattern to search for, as a string.
arrayThe input array.
flags
       If set to PREG_GREP_INVERT, this function returns
       the elements of the input array that do not match
       the given pattern.
      
   Returns an array indexed using the keys from the
   array array,  or false on failure.
  
If the regex pattern passed does not compile to a valid regex, an E_WARNING is emitted.
Example #1 preg_grep() example
<?php
// return all array elements
// containing floating point numbers
$fl_array = preg_grep("/^(\d+)?\.\d+$/", $array);
?>