解析取模运算% 和位与运算& 之间的关系详解

#include <stdio.h>

int main (void)
{
    unsigned int MAX = 32;
    unsigned int index = 31;

    index = 31;
    index = (index + 1) % MAX; // 这个容易理解
    printf ("index = %d\n", index);

    index = 31;
    index = (index + 1) & (MAX - 1); // 这个运算效率高
    printf ("index = %d\n", index);

return;
}

$ ./a.exe
index = 0
index = 0