string _hex2bits(char s) { int num; if ('0' <= s &;&; s <= '9'){ num = s - '0'; } else{ num = s - 'A' + 10; } string str; for (int i = 0; i < 8; i++) { int mod = num % 2; str.push_back('0' + mod); num = num / 2; } reverse(str.begin(), str.end()); return str; } int _bits2num(string&; str) { int result = 0; int base = 1; for (int i = str.length()-1; i >= 0; i--) { if (str[i] == '1'){ result += base; } base *= 2; } return result; } char _num2char(int num) { assert(num >= 0 &;&; num <= 63); if (0 <= num &;&; num <= 25) { return 'A' + (num - 0); } else if (26 <= num &;&; num <= 51) { return 'a' + (num - 26); } else if (52 <= num &;&; num <= 61) { return '0' + (num - 52); } else if (num == 62) { return '+'; } else { return '//'; } } void hex2base64(string&; str) { transform(str.begin(), str.end(), str.begin(), ::toupper); int mod = str.length() % 3; mod = mod == 0 ? -1 : 3 - mod; string tmp; for (int i = 0; i < str.length(); i++){ tmp += _hex2bits(str[i]); } for (int i = 0; i+6 <= tmp.length(); i = i+6) { string base64bits = tmp.substr(i, 6); int num = _bits2num(base64bits); cout << _num2char(num); } for (int i = 0; i < mod+1; i++) { cout << '='; } } int main() { string test1 = "1A2"; hex2base64(test1); return 0; }