$re = '/\bid\b=\[(.+?)\]/m';
$str = '@client.test.annotations.TestInfo(id=[]) //ignore this time
@org.testng.annotations.Test(alwaysRun=true,...
@client.test.annotations.TestInfo(id=[C10137, C12121])
@org.testng.annotations.Test(alwaysRun=true,...
@client.test.annotations.TestInfo(id=[C10137])
@org.testng.annotations.Test(alwaysRun=false, expectedExceptions=[]..';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php