如何显式丢弃out参数？ [英] How to explicitly discard an out argument?

问题描述

我正在拨打电话：

myResult = MakeMyCall(inputParams, out messages);

但我实际上并不关心消息。如果它是输入参数，我不在乎，我只是传入一个null。如果这是回报，我不在乎，就别管它了。

but I don't actually care about the messages. If it was an input parameter I didn't care about I'd just pass in a null. If it was the return I didn't care about I'd just leave it off.

是否可以用out做类似的事情，还是需要声明一个变量，然后将其忽略？

Is there a way to do something similar with an out, or do I need to declare a variable that I will then ignore?

推荐答案

从C＃7.0开始，可以避免预先声明参数并忽略它们。

Starting with C# 7.0, it is possible to avoid predeclaring out parameters as well as ignoring them.

public void PrintCoordinates(Point p)
{
    p.GetCoordinates(out int x, out int y);
    WriteLine($"({x}, {y})");
}

public void PrintXCoordinate(Point p)
{
    p.GetCoordinates(out int x, out _); // I only care about x
    WriteLine($"{x}");
}

来源： https://blogs.msdn.microsoft.com/dotnet/2017/03/09/ new-features-in-c-7-0 /

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