什么是'？'在C ++中做？ [英] What does '?' do in C++?

问题描述

int qempty()
{
    return (f == r ? 1 : 0);
}

在上述代码段中，？ 意思？我们可以用什么替换它？

In the above snippet, what does "?" mean? What can we replace it with?

推荐答案

这通常被称为条件运算符 ，并且在使用时如下：

This is commonly referred to as the conditional operator, and when used like this:

condition ? result_if_true : result_if_false

...如果条件计算 true ，表达式计算为 result_if_true ，否则计算为 result_if_false 。

... if the condition evaluates to true, the expression evaluates to result_if_true, otherwise it evaluates to result_if_false.

这是句法糖，在这种情况下，它可以替换为

It is syntactic sugar, and in this case, it can be replaced with

int qempty()
{ 
  if(f == r)
  {
      return 1;
  } 
  else 
  {
      return 0;
  }
}

注意：请将？：作为三元运算符，因为它是语言中唯一的三元运算符他们正在使用。

Note: Some people refer to ?: it as "the ternary operator", because it is the only ternary operator (i.e. operator that takes three arguments) in the language they are using.

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