我用C语言 写一个函数返回参数二进制中 1 的个数的三种不同方法

1.
#include<stdio.h>
int count_one_bits(unsigned int value)
{
         int count=0;
         while(value)
           {
                  if(value&1==1)
                          count++;
                          value>>=1;
           }
         return count;
}

int main ()
{
           int ret=0,num=0;
           scanf("%d",&num);
           ret=count_one_bits(num);
           printf("%d\n",ret);
           system("pause");
           return 0;
}
2.
#include<stdio.h>
int main ()
{
          int num=0;
          int ret=0;
          scanf("%d",&num);
          ret=count_one_bits(num);
          printf(" %d\n",ret);
          system("pause");
          return 0;
}
int count_one_bits(int n)
{
          int count=0;
          while(n)
             {
                      if(n%2==1)
                            {
                                          count++;
                             }
                       n=n/2;
             }
           return count;
}
3.
#include<stdio.h>
int main ()
{
         int num = 0;
         int set = 0;
         scanf("%d",&num);
         set = count_one_bits(num);
         printf(" %d\n",set);
         system("pause");
         return 0;
}
int count_one_bits( int n )
{
         int count = 0;
         int i = 0;
         for(i = 0;i < 32;i++)
              {
                    if((n >>i )& 1 == 1)
                           {
                                         count++;
                           }
               }
          return count;
}