比如：将一个16进制0xFD，即11111101，反向，输出10111111，即0xBF。

#include <stdio.h>

unsigned char reverseBits(unsigned char num) {
    unsigned char reverse_num = 0;
    int i;

    for (i = 0; i < 8; i++) {
        if ((num & (1 << i)))
           reverse_num |= 1 << ((8 - 1) - i);   
   }

    return reverse_num;
}

int main() {
    unsigned char original = 0xFD; // 11111101
    unsigned char reversed = reverseBits(original); // 反转后的结果

    printf("Original: 0x%02X\n", original);
    printf("Reversed: 0x%02X\n", reversed); // 反转后的值

    return 0;
}