src/Strings/Strings.php
public function strpos($needle, $offset = 0)
    {
        $function = static::$functions[(int) static::$useMbstring]['strpos'];

        return $function($this->string, $needle, $offset);
    }
public function strpos($needle, $offset = 0)
    {
        $function = static::$functions[(int) static::$useMbstring]['strpos'];

        return $function($this->string, $needle, $offset);
    }
public function strpos ( $ needle , $ offset = 0 ) { $ function = static :: $ functions [ ( int ) static :: $ useMbstring ] [ 'strpos' ] ; return $ function ( $ this -> string , $ needle , $ offset ) ; }
Strpos function. Use mbstring extension if loaded.

@param  string $needle The string to find in haystack.
@param  int    $offset The search offset. If it is not specified, 0 is used.
@return mixed False if not found, else position.
Strpos function . Use mbstring extension if loaded .