Caluclates the AT - CG ratio of a file containing "ATCG\n"

atcgratio.cpp

// Caluclates the AT - CG ratio of a file containing "ATCG\n"
// Usage: atcgratio.out INFILE
#include <iostream>
#include <string>
#include <fstream>
#include <cstdlib>
using namespace std;

int main(int argc,char **argv)
{
    string line;
    size_t at_count =0;
    size_t cg_count =0;
    size_t i;
    char c;
    ifstream in(argv[1],ios::in);
    if(!in.is_open()) return EXIT_FAILURE;
    
    while(getline(in,line,'\n')){
          for(i=0;i<line.size();i++) {
            c=line.at(i);
          if(c == 'A' || c == 'T')
            at_count++;
        if(c == 'C' || c == 'G')
          cg_count++; 
         }
	}
    
    
    in.close();
      std::cout << "AT count: " << at_count << endl;
      std::cout << "CG count: " << cg_count << endl;
     std::cout << "ratio  " << ((double)at_count / (double)cg_count) << endl;
    return 0;
}