計數兩個數中的位數並比較[C]

Question

我想編寫一個程序來比較兩個數中的1位數。我想比較任意兩個數字之間的位，以找出二進制數在1和0中的不同位置。換句話說，「異或」（XOR）關係。

一樣，如果22（其具有10110二進制），並將其與15比較（其具有01111二進制）

第一個是10110。 第二個是01111。

結果：11001。

答案是25，但我想得到的是3有三個不同的1 s和0 s。

Answer 1

要尋找不同的位，則需要XOR值：

unsigned int first = 22; 
unsigned int second = 15; 
unsigned int result = first^second; // only the bits that are different 
             // will be set to 1 in result 

要統計result 1位，你可以使用：

unsigned int CountBits(unsigned int n) { 

    unsigned int count = 0; 
    while(n) { 
     count += n & 0x01; // checks the least significant bit of n 
          // if the bit is 1, count is incremented 
     n >>= 1; // shift all bits of n one to the right 
       // if no 1 bits are left, n becomes 0 and the loop ends 
    } 
    return count; 
} 

unsigned int count = CountBits(result); 

要做到這一點在一步：

unsigned int count = CountBits(first^second); 

在某些系統上，可以使用POPCNT指令代替。

---

更新 - 完整的示例：

#include <stdio.h> 

unsigned int CountBits(unsigned int n) { 

    unsigned int count = 0; 
    while(n) { 
     count += n & 0x01; 
     n >>= 1; 
    } 
    return count; 
} 

int main(void) { 

    unsigned int first = 22; 
    unsigned int second = 15; 
    unsigned int result = first^second; 

    unsigned int count = CountBits(result); 

    printf("result: %u - count: %u\n", result, count); 

    return 0; 
} 

打印：

result: 25 - count: 3 

---

或者一個額外的功能：

#include <stdio.h> 

unsigned int CountBits(unsigned int n) { 

    unsigned int count = 0; 
    while(n) { 
     count += n & 0x01; 
     n >>= 1; 
    } 
    return count; 
} 

unsigned int CountDifferentBits(unsigned int n1, unsigned int n2) { 

    return CountBits(n1^n2); 
} 

int main(void) { 

    unsigned int count = CountDifferentBits(22, 15); 

    printf("Different bits count: %u\n", count); 

    return 0; 
} 

Answer 2

int count_bit(unsigned int x, unsigned int y){ 
int x1[31], y1[31]; 

unsigned int x_count = sizeof(x) * 8 - 1; /*x is of "unsigned int" type*/ 
unsigned int y_count = sizeof(y) * 8 -1; 

for (int i = 0; i<=x_count; i++){ 
    x1[i] = x << i;} 
for (int j = 0; j<= y_count;j++){ 
    y1[j] = y << j;} 

while((i<= x_count) && (j<= y_count)){ 
    if(x1[i] != y1[j]){ 
     count++; 
     i++; 
     j++; 
     return count;} 
    else 
     return 0; 
}