C：如果解释（退出（0），0）{} code线 [英] C: explain if(exit(0),0){} line of code

问题描述

我学习C和作为练习，我试着写一个简单的程序，没有任何分号。我有一些麻烦替换返回0 语句，但我发现，这是办法做到这一点在C（唯一）：如果（退出（0），0）{} 。

I am learning C and as an exercise, I'm trying to write a simple program without any semicolons. I've had some trouble with replacing return 0 statement but I've found that this is (the only?) way to do it in C: if(exit(0),0){}.

是如何执行这一说法的工作？

How exactly does this statement work?

我知道退出（）从 STDLIB 是一个无效的功能，但我不明白什么 0 部分的如果作品（其余的我很清楚）。

I know that exit() from stdlib is a void function but I don't understand what the ,0 part in the if works (the rest is clear to me).

推荐答案

的，经营者使用C会评估它的参数，返回第二个值。所以前pression

The , operator in C evaluates both its arguments, and returns the value of the second one. So the expression

exit(0), 0

通话退出（0）键，返回0所以，code你贴实际上相当于：

calls exit(0) and returns 0. So the code you posted is effectively equivalent to:

exit(0);
if (0) {}

然而，退出（）应终止该进程，所以这应该从来没有真正回来。这个成语只是被用来prevent虚假编译器警告。

However, exit() should terminate the process, so this should never actually return. The idiom is just being used to prevent spurious compiler warnings.

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