什么是“--"?C/C++ 中的运算符? [英] What is the "-->" operator in C/C++?

问题描述

阅读C++/STL的隐藏特性和暗角 在 comp.lang.c++.moderated 上，我完全惊讶于以下代码段在 Visual Studio 2008 和 G++ 4.4 中编译和运行.

After reading Hidden Features and Dark Corners of C++/STL on comp.lang.c++.moderated, I was completely surprised that the following snippet compiled and worked in both Visual Studio 2008 and G++ 4.4.

代码如下:

#include <stdio.h>
int main()
{
    int x = 10;
    while (x --> 0) // x goes to 0
    {
        printf("%d ", x);
    }
}

输出:

9 8 7 6 5 4 3 2 1 0

我认为这是 C，因为它也适用于 GCC.这在标准中是在哪里定义的，它是从哪里来的?

I'd assume this is C, since it works in GCC as well. Where is this defined in the standard, and where has it come from?

推荐答案

--> 不是运算符.它实际上是两个独立的操作符，-- 和 >.

--> is not an operator. It is in fact two separate operators, -- and >.

条件的代码递减x，同时返回x的原始(未递减)值，然后将原始值与0进行比较使用 > 运算符.

The conditional's code decrements x, while returning x's original (not decremented) value, and then compares the original value with 0 using the > operator.

为了更好地理解，该语句可以写成如下:

while( (x--) > 0 )

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