int ten digit limit?

[tlpog]

A problem from a beginner's howto on C++. Using g++.

#include <iostream>
using std::cout;
using std::cin;
using std::endl;

int num;
int factor;
int conv;
int remainder;
int dec;
int figure;

int main()
{
  factor = 1;
  conv = 0;

  cout << "Enter binary number: ";
  cin >> num;
  figure = num;

  while ( num > 0)
    {
      remainder = num % 10;
      conv = ( factor * remainder) + conv;
      factor = factor * 2;
      dec = conv;
      num = num / 10;
    }

  cout << endl << figure << " to decimal is " << dec << endl;
  return 0;
 }

The program converts a binary to decimal. I encounter a problem, however when I try to enter 11 digit numbers and beyond. The program displays the digit as 0 and the subsequent decimal solution as 0. I suspect this might have something to do with my 32bit processor? If not, then what is the limit about? Links and suggestions appreciated, thank you.

[Duthomhas]

That's it exactly. The largest value an int can hold is 4294967295, which is ten digits. Even though the user is entering a number like 100101, it is still read as a decimal number, hence the limit in digits.

I would suggest getting a string from the user, verify that it is composed of nothing but '0's and '1's, and then convert the string, character by character, to a decimal number. Then your limit will be 32 digits/bits. Well, 31 if you continue to use a signed int.

Have fun!