“出"的目的是什么?调用方的关键字(在 C# 中)? [英] What is the purpose of the "out" keyword at the caller (in C#)?

问题描述

当一个 C# 函数有一个输出参数时，你要明确如下:

When a C# function has an output parameter, you make that clear as follows:

private void f(out OutputParameterClass outputParameter);

这表明在调用函数时不必初始化参数.但是，在调用这个函数时，必须重复out关键字:

This states that the parameter does not have to be initialized when the function is called. However, when calling this function, you have to repeat the out keyword:

f(out outputParameter);

我想知道这有什么用.为什么需要重复部分功能规范?有人知道吗?

I am wondering what this is good for. Why is it necessary to repeat part of the function specification? Does anyone know?

推荐答案

我得到的最佳答案是 plinth:

The best answer I got was posted as a comment by plinth:

重复 out/ref 的最重要原因是，如果您调用的函数被重构为不同的签名，您将收到编译错误.最值得注意的是，如果参数从非输出变为输出，您马上就会知道.

The most important reason for the repeating of out/ref is that if the function you're calling gets refactored with a different signature, you will get a compile error. Most notably, if a parameter goes from non-out to out, you'll know right away.

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