正则表达式，多次出现

I would like to know how to get multiple occurrences from a regex.

$str = "Some validations <IF TEST>firstValue</IF> in <IF OK>secondValue</IF> end of string.";
$do = preg_match("/<IF(.*)>.*<\/IF>/i", $str, $matches);

This is what I've done so far. It works if I have only 1 , but if I have more it doesn't return the right values. Here is the result:

Array ( [0] => firstValue in secondValue [1] => TEST>firstValue in

I need to get the "TEST" and the "OK" values.

EDIT: I've brought the modifications suggested, thanks a lot it works fine ! However, I am now trying to add a elsif parameter and can't get it to work well. Here is what I've done:

$do = preg_match_all("~<IF([^<>]+)>([^<>]+)(</IF>|<ELSEIF([^<>]+)>([^<>]+)</IF>)~", $str, $matches, PREG_SET_ORDER);

and the results is

Array 
( 
    [0] => Array 
           (
              [0] => firstValuesecondValue 
              [1] => TEST 
              [2] => firstValue 
              [3] => secondValue 
              [4] => TEST1 
              [5] => secondValue 
           ) 
    [1] => Array 
           ( 
               [0] => thirdValue 
               [1] => OK 
               [2] => thirdValue 
               [3] => 
           ) 
) 

Is there a way to make my array more clean ? It has many elements which are useless like the [0][4] etc.

You should make the regex more specific. The .* that you are using should either be less greedy, or better yet disallow other angle brackets:

~<IF([^<>]+)>([^<>]+)</IF>~i

More importantly, you should use preg_match_all, not just preg_match.

preg_match_all("~<IF([^<>]+)>([^<>]+)</IF>~i", $str, $matches, PREG_SET_ORDER);

That'll give you a nested array like:

[0] => Array
    (
        [0] => <IF TEST>firstValue</IF>
        [1] =>  TEST
        [2] => firstValue
    )

[1] => Array
    (
        [0] => <IF OK>secondValue</IF>
        [1] =>  OK
        [2] => secondValue
    )

The answers pointing out that you should use preg_match_all are correct.

But there is another problem: the .* is greedy by default. This will cause it to match both tags in a single match, so you need to make the star non-greedy (i.e. lazy):

/<IF(.*?)>.*?<\/IF>/i

Use a non-greedy match .*? and preg_match_all for this purpose.

Use this code:

$string = "Some validations <IF TEST>firstValue</IF> in <IF OK>secondValue</IF> end of string.";
$regex = "/<IF (.*?)>.*?<\/IF>/i";
preg_match_all($regex, $string, $matches);
print_r($matches[1]);

You regex is good but you have to use the non-greedy mode adding the ? char and use the preg_match_all() function.