Question

How to perform a preg_match this

 $needle = '"pid": "20"';
 $haystack = '"pid": "1"' . '"pid": "12"' . '"pid": "20"' . '"pid": "14"';

and by the way the needle numeric value is not static
i am novice at preg_match

Answer 1

[0-9]+  // Matches 1 or more numbers from 0 to 9

This is exactly what you asked for, but if you provide what your expected output is or how you receive your haystack, there may be a better suited solution than regular expressions.

$needle   = '/"pid": "[0-9]+"/';
$haystack = '"pid": "1"' . '"pid": "12"' . '"pid": "20"' . '"pid": "14"';

preg_match_all($needle,$haystack,$matches);

$matches Output

(
    [0] => Array
        (
            [0] => "pid": "1"
            [1] => "pid": "12"
            [2] => "pid": "20"
            [3] => "pid": "14"
        )

)

To learn more about regular expressions, check out this basic syntax reference.