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up vote 6 down vote favorite
2

Is it possible to use a regular expression with the php function array_key_exists()?

For example:

$exp = "my regex";  
array_key_exists($exp, $array);

Thank you!

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3 Answers

up vote 10 down vote accepted

You can extract the array keys using array_keys() and then use preg_grep() on that array:

function preg_array_key_exists($pattern, $array) {
    $keys = array_keys($array);    
    return (int) preg_grep($pattern,$keys);
}

.

$arr = array("abc"=>12,"dec"=>34,"fgh"=>56);

var_dump(preg_array_key_exists('/c$/',$arr)); // check if a key ends in 'c'.
var_dump(preg_array_key_exists('/x$/',$arr)); // check if a key ends in 'x'.

function preg_array_key_exists($pattern, $array) {
    // extract the keys.
    $keys = array_keys($array);    

    // convert the preg_grep() returned array to int..and return.
    // the ret value of preg_grep() will be an array of values
    // that match the pattern.
    return (int) preg_grep($pattern,$keys);
}

Output:

$php a.php
int(1)
int(0)
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that's an interesting way of doing, I'm going ot try it right now ! thanks a lot for your time – Bacon Mar 18 '10 at 16:10
instead of flipping you can use array_keys() – zerkms Mar 18 '10 at 16:53
@zerkms: Thats perfect. Thanks :) – codaddict Mar 18 '10 at 16:55
up vote 0 down vote

there is no such function out of the box. you have to implement it with yourself.

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up vote 0 down vote

No, I'm afraid not. You can iterate the array keys and perform matches on those:

$keys = array_keys($array);
foreach ($keys as $key)
  if (preg_match($exp, $key) == 1)
    return $array[$key];
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or just if(preg_match(...)) in the case of multiple result occurencies. – zerkms Mar 18 '10 at 15:41
@zerkms: preg_match() only matches the first occurrence of the pattern. Therefore it can only return 0 or 1. Please see php.net/preg_match – Andrew Moore Mar 18 '10 at 15:44
ah, my bad, sorry – zerkms Mar 18 '10 at 16:06

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