base64 encoder

base64enc.cc

#include <iostream>
#include <bitset>
#include <vector>
#include <string>
#include <cmath>
int main(int argc, char *argv[])
{
  std::string table=
    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    "abcdefghijklmnopqrstuvwxyz"
    "0123456789+/";
  std::string in,out;std::cin>>in;
  std::string::iterator iter;
  std::bitset<24> data24;
  int blank=ceil(in.size()/3.0)*3-in.size();
  in.resize(ceil(in.size()/3.0)*3);
  for(int i=0;i<in.size()/3;i++){
    data24|=*iter++;data24<<=8;
    data24|=*iter++;data24<<=8;
    data24|=*iter++;
    out+=table.at((data24>>6*3).to_ulong());data24<<=6;
    out+=table.at((data24>>6*3).to_ulong());data24<<=6;
    out+=table.at((data24>>6*3).to_ulong());data24<<=6;
    out+=table.at((data24>>6*3).to_ulong());
  }
  for(int i=1;i<=blank;i++)
    out.at(out.size()-i)='=';
  std::cout<<out<<std::endl;
  return 0;
}