C ++ - 回报X，Y;要点是什么？ [英] C++ -- return x,y; What is the point?

问题描述

我在C和C ++编程了了几年，现在我只是现在采取了大学课程在里面，我的书有一个例子像这样的功能：

I have been programming in C and C++ for a few years and now I'm just now taking a college course in it and our book had a function like this for an example:

int foo(){
  int x=0;
  int y=20;
  return x,y; //y is always returned
}

我从来没有见过这样的语法。事实上，我从来没有见到过，参数列表外使用运营商。如果是总是返回，虽然，那还有什么意义呢？是否存在这样一个return语句将需要这样创建的情况下？

I have never seen such syntax. In fact, I have never seen the , operator used outside of parameter lists. If y is always returned though, then what is the point? Is there a case where a return statement would need to be created like this?

（另外，我标记的c以及因为它适用于，虽然我的书特别是C ++）

(Also, I tagged C as well because it applies to both, though my book specifically is C++)

推荐答案

逗号操作符在主要用于像这样的语句：

The comma operator is primarily used in for statements like so:

for( int i=0, j=10; i<10; i++, j++ )
{
    a[i] = b[j];
}

第一个逗号不是逗号操作符，它的声明语法的一部分。第二个的是的逗号操作符。

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