A C program to count set bits in an integer

We can write solution for this problem in two way i.e.

1. Using non-recursive method
2. Using recursive method.

Here is the C program to count set bits in an integer with the help of bit-wise operator using non-recursive method.

/* 1. Non-recursive : C program to Count set bits in an integer */
#include<stdio.h> 
/* 
 * numOfSetBits() : to get number of set bits of 
 * positive integer n using bit-wise operator
 */
int numOfSetBits ( unsigned int num ) 
{ 
  int numSetBits = 0; 
  while ( num ) 
  { 
    numSetBits += num & 1; 
    num >>= 1; 
  } 
  return numSetBits; 
}  
int main() 
{ 
   int n = 14, result = 0; 
   result = numOfSetBits( n );
   printf ( "The number of set bits are %d\n", result );
   return 0;
} 

Here is the C program to count set bits in an integer with the help of bit-wise operator using recursive method.

/* 2. Recursive : C program to Count set bits in an integer */
#include<stdio.h> 
/* 
 * numOfSetBits() : to get number of set bits of 
 * positive integer n using bit-wise operator
 */
int numOfSetBits ( int num ) 
{     
    if ( num == 0) 
         return 0;      
    else      
         /* if last bit set add 1 else add 0 */
         return (num & 1) + numOfSetBits ( num >> 1); 
}  
int main() 
{ 
   int n = 14, result = 0; 
   result = numOfSetBits( n );
   printf ( "The number of set bits are %d\n", result );
   return 0;
}

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