Question

How to check if an integer contains an even or odd number of bits set in C

Answer 1

#include <stdio.h>
#include <stdbool.h>

bool hasEvenOrOddBitsSet(int num) {
    int count = 0;
    while (num) {
        count += num & 1; // Increment count if the least significant bit is 1
        num >>= 1;        // Right shift the number by 1
    }
      
    return count % 2 == 0; // Return true if count is even
}
  
int main() {
    int num = 42; // 0010 1010
  
    if (hasEvenOrOddBitsSet(num)) {
        printf("The number has an even number of bits set to 1.\n");
    } else {
        printf("The number has an odd number of bits set to 1.\n");
    }
    
    return 0;
}
  
  
  
/*
run:
  
The number has an odd number of bits set to 1.
  
*/

 

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