php正则表达式找到匹配

Question

I've got the following code:

if (preg_match('/fl=(.*)&/', $resp, $matches)) {
    $temp=$matches[0];
    $fl= str_replace("fl=", '',$temp);
   }

I want to get the text from $resp that is after fl= and before the next &

The problem I am having is that it ignores the first few &'s. The output I'm currently getting is Email&errorType=format&" what i want is Email

Answer 1

You need to use lazy matching .*? or negated character class [^&]*.

$resp = "/fl=123&gh=word&more=params";
if (preg_match('/fl=(.*?)&/', $resp, $matches)) {
    $fl=$matches[1];
    echo $fl;
   }

See IDEONE demo

Note that .* is too greedy, meaning that it matches as many characters to the right of the string as possible. It happens so because the regex engine grabs the whole substring up to the last & and then backtracks to find that it can actually capture that whole substring. With .*?, we get the closest next &.