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phpregexarrayspreg-match

How to search in an array with preg_match?

How do I search in an array with preg_match?

Example:

<?php
if( preg_match( '/(my\n+string\n+)/i' , array( 'file' , 'my string  => name', 'this') , $match) )
{
    //Excelent!!
    $items[] = $match[1];
} else {
    //Ups! not found!
}
?>
Solution

  • In this post I'll provide you with three different methods of doing what you ask for. I actually recommend using the last snippet, since it's easiest to comprehend as well as being quite neat in code.

    How to get the matching elements of an array

    There is a function dedicated for just this purpose, preg_grep. It will take a regular expression as first parameter, and an array as the second.

    See the below example:

    $haystack = array (
  'say hello',
  'hello stackoverflow',
  'hello world',
  'foo bar bas'
);

$matches  = preg_grep ('/^hello (\w+)/i', $haystack);

print_r ($matches);

    output

    Array
(
    [1] => hello stackoverflow
    [2] => hello world
)

    Documentation

    How to extract only the matching text from array elements?

    array_reduce with preg_match can solve this issue in clean manner; see the snippet below.

    $haystack = array (
  'say hello',
  'hello stackoverflow',
  'hello world',
  'foo bar bas'
);

function _matcher ($m, $str) {
  if (preg_match ('/^hello (\w+)/i', $str, $matches))
    $m[] = $matches[1];

  return $m;
}

// N O T E :
// ------------------------------------------------------------------------------
// you could specify '_matcher' as an anonymous function directly to
// array_reduce though that kind of decreases readability and is therefore
// not recommended, but it is possible.

$matches = array_reduce ($haystack, '_matcher', array ());

print_r ($matches);

    output

    Array
(
    [0] => stackoverflow
    [1] => world
)

    Documentation

    Using array_reduce seems tedious, is there another way?

    Yes, and this one is actually cleaner though it doesn't involve using any pre-existing array_* or preg_* function.

    Wrap it in a function if you are going to use this method more than once.

    $matches = array ();

foreach ($haystack as $str) 
  if (preg_match ('/^hello (\w+)/i', $str, $m))
    $matches[] = $m[1];

    Documentation