《c陷阱与缺陷》笔记--移位运算

 

#include <stdio.h>

int main(void){
        int a = 2;
        a >> 32;
        a >> -1;
        a << 32;
        a << -1;
        return 0;
}

上面代码编译时出现如下错误：

 

yiwei.c: In function 'main':
yiwei.c:5:2: warning: right shift count >= width of type [enabled by default]
yiwei.c:6:2: warning: right shift count is negative [enabled by default]
yiwei.c:7:2: warning: left shift count >= width of type [enabled by default]
yiwei.c:8:2: warning: left shift count is negative [enabled by default]

因为移位有一条规则：

如果被移位的对象长度是n位，那么移位技术必须大于或等于0，而且小于n。