[SOLVED] explanation of code?

[ali_2kool2002]

 

Hi can someone tell me how the code below works? im not sure what preg_match does with all those characters after it ? ??? ???

 

foreach ($_POST as $k => $v) {

    		if (preg_match('|^sub_([\d]+)\z|', $k, $match)) {
        $button = $match[1];

[Guest prozente]

|^sub_([\d]+)\z|

| is the pattern delimiter
^ means from the start of the string
sub_ is some text it wants to match from the start of the string
() are used to create back references, it'll capture this text in the returned array
[] are used to define a character class
\d stands for decimal digit, it'll match numbers 0-9, so this is the character class
+ means the character class will match at least one char for a char class
so ([\d]+) will be returned as the first back reference
\z stands for the end of the string

 

so sub_123 will pass this regex and return 123 as the first back reference

sub_abc1 will not pass this regex as it has the alpha characters in it