problem with converting base code

[steven8]

hi, i have written this code for converting from base 10 to base 2 but it dose not work for numbers having more than 3 digits.(like 1231) if anyone can help me?
thanks

 #include<iostream>
using namespace std;
#include<math.h>

int main()
{	int num;
cout<<"enter a number"<<endl;
cin>>num;
int i=0;
	unsigned long k=0;
	while(num>=1){
		k+=(num%2)*powf(10,i);
		num/=2;
		i++;}


	cout<<"your number in 2 base    "<<k<<endl;
return 0;}

[dhayden]

It sounds like your unsigned long is 32 bits, which has room for only 10 digits (when the digits are 0 and 1). So you're overflowing the size of unsigned long.

Rather than creating a new number, why not put the results into a string? That way you don't have to worry about the size. Just peel off the least significant bit at each iteration of the loop and append it to a string. When you're done, reverse the string to get it in the right order.