"C" to find the number of 1 in the binary of a number

To find the number of binary 1 of a number

1, through the method of modular removal

#define _crt_secure_no_warnings 1
#include <stdio.h>
#include <stdlib.h>
int main ()
{   
	int i = 0;
	int count = 0;
	printf ("Please enter a number: \ n");
	scanf ("%d", &i);
	while (i)
	{
		if (i%2==1)
	    {
		   count++
	    }
		i = I/2;
	}
	printf ("Number of 1 in this number is:%d 1\n", count);
}

2, but this will be flawed, if you enter a negative, the control of the symbol is not very good

Write it in a separate function and pass it into unsigned int num to resolve

#define _crt_secure_no_warnings 1
#include <stdio.h>
#include <stdlib.h>

int  count _one_bits (unsigned int num)
{
	int count = 0;
    while (num)
	{
		if (num%2 = 1)
		{
			count++
		}
		num = NUM/2;
	}
	return count;
}

int main ()
{	
	int num = one;
	int result = 0;
	result = Count_one_bits (num);
	printf ("Number of 1 in this number is:%d 1\n", result);
	return 0;
}

3, because the general number of bits are 32 bits, there may not be complete statistics of the number of 1, with the loop to solve

#define _crt_secure_no_warnings 1
#include <stdio.h>
#include <stdlib.h>
int  count_one _bits (unsigned int num)
{
	int count = 0;
	int i = 0; 
	For (I=1 i<32; i++)
	{
		if (num%2 = = 1)
		{
			count++;
		}
		num = NUM/2;
	}
    return count;
}
int main ()
{	
	int num = 0;
	int result = 0;
	printf ("Please enter a number: \ n");
	scanf ("%d", &num);
	result = Count_one_bits (num);
	printf ("%d of the binary number of 1 of the number is:%d 1\n", num,result);
	return 0;
}

4, the number of cycles is 32 times, so that the program is a bit slow, and the method can be a good solution

#define _crt_secure_no_warnings 1
#include <stdio.h>
#include <stdlib.h>
int  count_one _bits (unsigned int num)
{
	int count = 0;
	while (num)
	{
	num = num& (num-1);
		count++;
	}
    return count;
}
int main ()
{	
	int num = 0;
	int result = 0;
	printf ("Please enter a number: \ n");
	scanf ("%d", &num);
	result = Count_one_bits (num);
	printf ("%d of the binary number of 1 of the number is:%d 1\n", num,result);
	return 0;
}