Question

Alright i know this question might some weird , but still i wanted to demystify it.

1.)an int type in C can stores number in the range of -2147483648 to 2147483647.

2.)If we append an unsigned it front of it , the range would become 0 to 2147483647.

3.)The thing is , why do we even bother to use the keyword unsigned when the code below could actually works.

The Code:

#include <stdio.h>

int main(void)
{
    int num = 2147483650;

    printf("%u\n" , num);

    return 0;
}

4.)As you see , i can still print out the integer as unsigned type if I use the %u specifier and it will print me the value 2147483650.

5.)Even if I create another integer type with value 50 and sum it up with num , although it’s overflow but yet I still can print out the correct sum value by using %u specifier.So why unsigned keyword is still a necessity??

Thanks for spending time reading my question.

Answer 1

Considering only Q3, “Why do we bother to use unsigned”, consider this program fragment:

int main(void) {

  int num = MAX_INT;
  num += 50;

  printf("%u\n", num); /* Yes, this *might* print what you want */

  /* But this "if" almost certainly won't do what you want. */
  if(num > 0) {
    printf("Big numbers are big\n");
  } else {
    printf("Big numbers are small\n");
  }
} 

We use “unsigned” because unsigned int behaves differently from int. There are more interesting behaviors than just how printf works.