求解一个左移运算的问题

天地散人

#include <stdio.h>

void main()
{
        int i = 2 << 34;
        int m = 2;
        int n = m << 34;
        printf("%d %d\n", i, n);
}


输出结果是： 0  8。
结果不应该是一样的吗，为什么会不同？

linux_c_py_php

未定义行为哈，移动的宽度比整形自身还宽，编译器都警告了。

myworkstation

linux_c_py_php 发表于 2013-11-22 09:33
未定义行为哈，移动的宽度比整形自身还宽，编译器都警告了。

顶楼上，补充一下标准中的原话：The integer promotions are performed on each of the operands. The type of the result is
that of the promoted left operand. If the value of the right operand is negative or is
greater than or equal to the width of the promoted left operand, the behavior is undefined.