comparing a signed and unsigned integer in c language

Question

#include <stdio.h>
int main(void)
{
    if (sizeof(int) > -10)
        printf("YES\n");
   else 
        printf("NO\n");
   return 0;
}

why it is printing NO instead of YES? Because the size of int is 4bytes as per the compiler.And it is greater than -10.

`sizeof()` returns an **unsigned** value, so it can never be less than 0. — Remy Lebeau, Aug 30 '18 at 01:03
I would also like to suggest that `printf("%zu\n", (size_t)-10)` may be enlightening. — zwol, Aug 30 '18 at 01:04
[Why is −1 > sizeof(int)?](https://stackoverflow.com/q/3100365/995714) — phuclv, Aug 30 '18 at 01:05
You have used < ( smaller than sign) which means it will print NO, as 4 is greater than -10. if (a < b) { prints yes if a is smaller. } else { prints no if b is smaller. } you have a = 4 and b = -10, thus it prints no. — R. Gurung, Aug 30 '18 at 01:09
@RahulGurung Did you try it? The correct behavior is actually "YES". — aschepler, Aug 30 '18 at 01:18
@RahulGurung See the duplicate, and/or look at [the Usual Arithmetic Conversions](https://en.cppreference.com/w/c/language/conversion#Usual_arithmetic_conversions) — aschepler, Aug 30 '18 at 01:26

score 3 · Answer 1 · answered Aug 30 '18 at 01:04

3

sizeof produces an unsigned value. When comparing a signed and unsigned integer, the signed value is converted to unsigned. The two’s complement value for -10 is much bigger than 4 when interpreted as unsigned.

answered Aug 30 '18 at 01:04

Govind Parmar

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Shouldn't `if (sizeof(int) < much_bigger_value)` be true? – Barmar Aug 30 '18 at 01:07
@Barmar because of your comment I realized that the OP was reporting an output of NO. I get an output of YES with his exact code. – Govind Parmar Aug 30 '18 at 01:22
1

The title says that `sizeof(int)` is less than `-10`. It is a bit unclear. – Osiris Aug 30 '18 at 01:26

comparing a signed and unsigned integer in c language

1 Answers1