Simple file reading

20121110.cpp

#include <string>
#include <fstream>
#include <iostream>
#include <sstream>
#include <cstdlib>
using namespace std;

static unsigned binary_string_to_int(const string &s)
{
    unsigned converted = 0;
    for(string::const_iterator it = s.begin(); it != s.end(); ++it) {
        if(*it != '0' && *it != '1')
            continue;
        (converted *= 2) += *it - '0';
    }
    return converted;
}

int main()
{
    ifstream in("input.txt");
    
    if(!in) {
        cerr << "error: can't open input.txt" << endl;
        exit(1);
    }
    
    string line;
    while(getline(in, line)) {
        istringstream ss(line);
        string op, val;
        
        if(ss >> op >> val) {
            cout << "got operator [" << op << "] and integer value [" <<
               binary_string_to_int(val) << "]" << endl;
        } else {
            cerr << "malformed input: " << line << endl;
        }
    }
}

input.txt

NOT 10100110   
  AND   00111101
OR       1011
XOR  11011100110111

output.txt

$ g++ -Wall -Wextra -pedantic -std=c++98 -O2 20121110.cpp -o 20121110

$ ./20121110
got operator [NOT] and integer value [166]
got operator [AND] and integer value [61]
got operator [OR] and integer value [11]
got operator [XOR] and integer value [14135]