I wanted to count asterisks from a string starting with foo 'fooarbazlujabazlewis*bazbazlewbaz' and i should be able to count asterisk from another string starting with luja in short I wanted the starting string to be changed programmatically
I tried below code, but it counts any asterisk even if foo is not at the beginning
preg_match_all('/(^foo\*)*(\*)/', '*foo*arbaz*luj*abaz*lewis*bazbazlewbaz');
the result is 6. but in this case, I wanted it to fail since foo is not at the beginning.
It is not the best application for a regex, but you can use
preg_match_all('~(?:\G(?!\A)|^foo)[^*]*\K\*~', $string, $matches)
See the regex demo. Details:
(?:\G(?!\A)|^foo) - either the end of the previous successful match or foo at the start of string[^*]* - zero or more chars other than *\K - discard the text matched so far\* - an asterisk.See the PHP demo:
$string = "foo*arbaz*luj*abaz*lewis*bazbazlewbaz";
echo preg_match_all('~(?:\G(?!\A)|^foo)[^*]*\K\*~', $string, $matches);
// => 5
Without a regex, you could simply check if foo appears at the start of string (using strpos) and then use substr_count to count the occurrences of asterisks:
$string = "foo*arbaz*luj*abaz*lewis*bazbazlewbaz";
if (strpos($string, "foo") === 0 ) {
echo substr_count($string, "*");
}
See this PHP demo.
strpos and 0, otherwise your condition will be true when foo isn't in the string.
if ( strpos($str, 'foo') === 0 ) echo substr_count($str, '*');