How to concatenate two integers in C

Question

Stack Overflow has this question answered in many other languages, but not C. So I thought I\'d ask, since I have the same issue.

How does one concatenate t

Answer 1

unsigned concatenate(unsigned x, unsigned y) {
    unsigned pow = 10;
    while(y >= pow)
        pow *= 10;
    return x * pow + y;        
}

Proof of compilation/correctness/speed

I avoid the log10 and pow functions, because I'm pretty sure they use floating point and are slowish, so this might be faster on your machine. Maybe. Profile.

Answer 2

here's another way to do it:

int concat(int x, int y) {
    int temp = y;
    while (y != 0) {
        x *= 10;
        y /= 10;
    }
    return x + temp;
}

who knows what performance you'll get. just try and see..

Answer 3

You can also use Macro to concatnate Strings ( Easy way )

#include<stdio.h>
#define change(a,b) a##b
int main()
 {
    int y;
    y=change(12,34);
    printf("%d",y);
    return 0;
 }

It has one Disadvantage. We can't pass arguments in this method