C ++什么是'int x =（anyInt1，anyInt2）;'意思？ [英] C++ What does 'int x = (anyInt1, anyInt2);' mean?

问题描述

可能重复：

为什么3,758,096,384< 1给出768

今天我发现下面的代码用gcc编译： / p>

Today I found out that following code compiles with gcc:

#include <iostream>

int main()
{
    int x = (23,34);

    std::cout << x << std::endl; // prints 34

    return 0;
}

为什么要编译？ <...> ...

Why does this compiles? What is the meaning of (..., ...)?

推荐答案

在C ++中， 是一个运算符，因此（23,34）是一个类似于（23 + 34）是一个表达式。在前者中，，是运算符，而在后者中， + 是运算符。

In C++, , is an operator, and therefore (23,34) is an expression just like (23+34) is an expression. In the former, , is an operator, while in the latter, + is an operator.

所以表达式（23,34）计算到最右边的操作数 34 这就是为什么你的代码输出 34 。

So the expression (23,34) evaluates to the rightmost operand which is 34 which is why your code outputs 34.

，不是函数调用中的运算符：

I would also like to mention that , is not an operator in a function call:

int m = max(a,b);

这里，它不作为运算符。

Here , acts a separator of arguments. It doesn't act as operator. So you pass two arguments to the function.

但是，

int m = max((a,b), c);

这里首先， second ，是一个分隔符。所以你仍然传递两个参数到函数，而不是三个，它等价于：

Here first , is an operator, and second , is a separator. So you still pass two arguments to the function, not three, and it is equivalent to this:

int m = max(b, c); //as (a,b) evaluates to b

希望有帮助。 ： - ）

Hope that helps. :-)

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