Question

The code is giving false answers. İf number equals 42, it turns it to 101010. Ok, it is true. But if number equals 4, it turns it to 99. I didn’t find the mistake. How can i fix the code?

#include<stdio.h>
#include<conio.h>
#include<math.h>

int main()
{
    int i,digit,number=4;
    long long bin= 0LL;
    i=0;
    while(number>0)   
    {
          digit=number%2;
          bin+=digit*(int)pow(10,i);
          number/=2;
          i++;
    }
    printf("%d ",bin);
    getch();   
}

Answer 1

Stop using floating point calculations for this. You are subject to the vagaries of floating point. When I ran your program with my compiler, the output was 100. But I guess your compiler treated the floating point pow differently.

A simple change to make the code behave, and use integer arithmetic only, would be like this:

#include<stdio.h>
#include<conio.h>
#include<math.h>

int main()
{
    int digit,number=4;
    long long scale,bin= 0LL;
    scale=1;
    while(number>0)   
    {
          digit=number%2;
          bin+=digit*scale;
          number/=2;
          scale*=10;
    }
    printf("%lld ",bin);
    getch();   
}

But I’d rather see the binary built up in a string rather than an integer.