A program that converts 16 bit positive number in binary

Question

i am trying to write a program such that if a % 2^j = 0 then it prints 1, else it prints 0 so at the end i get a 16 bit binary code. But i get no error and after i enter an input number (a) terminal crashes. Thank you for your help.

#include <math.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>

int main() {
  uint16_t a, j, b, mod;
  printf(" Please insert a number between 0 and 65535 \n ");
  scanf("%d", &a);

  j = 16;
  while (j > 0)
    ;
  {
    b = pow(j, 2);
    mod = a % b;
    if (mod == 0) {
      printf("%d", 1);
    } else {
      printf("%d", 0);
    }
    j = j - 1;
  }

  return 0;
}

Answer 1

You have undefined behavior as you use the %d format for scanf . This format specifier expects the argument to be a pointer to int .

Mismatching format specifier and argument type leads to UB.

For uint16_t use the macro SCNu16 (as documented in eg this reference ):

scanf("%" SCNu16, &a);