[C/C++] count 1 bits of input value by shifting.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21

#include <stdio.h>
#include <stdlib.h>
int count_1_bit_count(unsigned int);
int main(){
    int count = 0, a;
    a = 1023;
    count = count_1_bit_count(a);
    printf("%d有%d個位元為1\n\n", a, count);
    system("pause");
    return 0;
}
int count_1_bit_count(unsigned int n)
{
    int count = 0;
    for(count = 0; n != 0; n >>= 1L)
    {    
        if(n & 0x01)
            count++;
    }    
    return count;
}