A＆GT; = B＆GT; = C运营商C 2 [英] A>=B>=C operators in C?

问题描述

考虑：

#include<stdio.h>

int main() {
    if (2 >= 1 >= 1)
        printf("1\n");
    if (200 >= 100 >= 100)
        printf("2\n");
    return 0;
}

纽约纽约@：〜/ PRG $ GCC sample.c文件

nyc@nyc:~/PRG$ gcc sample.c

纽约纽约@：〜/ PRG $ ./a.out 1

nyc@nyc:~/PRG$ ./a.out 1

为什么这个方案只打印1即使以第二次的前pression值为TRUE？

Why does this program print only 1 even if the second expression evaluates to TRUE?

推荐答案

C不支持链接这样的运营商。你必须除以前pression一分为二，由逻辑运算符分隔的：

C doesn't support chaining operators like that. You'll have to divide that expression into two, seperated by the logical AND operator:

if(2 >= 1 && 1 >= 1)
if(200 >= 100 && 100 >= 100)

，否则它是作为执行

otherwise, it is executed as

if((2 >= 1) >= 1)
if((200 >= 100) >= 100)

和左侧部分将执行第一，将评估为1，如果该条件为真，将计算为0，如果是假的，因此，上述条件变得

and the left part will execute first and will evaluate to 1 if that condition is true and will evaluate to 0, if it is false and so, the above conditions becomes

if(1 >= 1) /* which is true */
if(1 >= 100) /* which is false */

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