RSA encryption implementation

long i;

        C = 1;
        for(int t=0;t<sss.length();t++)
        {
            for(i=0;i< e;i++)

                C=C*(string_to_hex(ccc))%n; // <- this part cannot use 

                                            // string_to_hex is string datatype
                    C = C%n;

        }