why does php starts with ? code example

Example 1: php string starts with

//php check if first four characters of a string = http
substr( $http, 0, 4 ) === "http";
//php check if first five characters of a string = https
substr( $https, 0, 5 ) === "https";

Example 2: startsWith() and endsWith() functions in PHP

function startsWith($haystack, $needle)
{
     $length = strlen($needle);
     return (substr($haystack, 0, $length) === $needle);
}

function endsWith($haystack, $needle)
{
    $length = strlen($needle);
    if ($length == 0) {
        return true;
    }

    return (substr($haystack, -$length) === $needle);
}