ASP.net C# VB.Net PHP
Swoole ASP/ADO/VBScript SQL语言 Python Python3 Diango C语言 Lua C++ Go语言 Revel Docker Ruby Perl Erlang R语言 Julia Apex OAuth 2.0 Arduino 编程经验 汇编语言 树莓派 游戏设计 MATLAB Elasticsearch Numpy F# Delphi HTCondor Rust 易语言 NSQ
用户登录
用户注册

分享至

成员访问中的问号在 C# 中是什么意思?

  • 作者: 大飞小晶
  • 来源: 51数据库
  • 2022-10-20

问题描述

谁能给我解释一下下面代码中成员访问中的问号是什么意思?

Can someone please explain to me what does the question mark in the member access in the following code means?

它是标准 C# 的一部分吗?尝试在 Xamarin Studio 中编译此文件时出现解析错误.

Is it part of standard C#? I get parse errors when trying to compile this file in Xamarin Studio.

this.AnalyzerLoadFailed?.Invoke(this, new AnalyzerLoadFailureEventArgs(AnalyzerLoadFailureEventArgs.FailureErrorCode.NoAnalyzers, null, null));

AnalyzerFileReference.cs 行195

推荐答案

Null Propagation operator在C#6中引入，只有对象this.AnalyzerLoadFailed不为null时才会调用该方法:

It is Null Propagation operator introduced in C# 6, it will call the method only if object this.AnalyzerLoadFailed is not null:

this.AnalyzerLoadFailed?.Invoke(this, new AnalyzerLoadFailureEventArgs(AnalyzerLoadFailureEventArgs.FailureErrorCode.NoAnalyzers, null, null));

等于:

if( this.AnalyzerLoadFailed != null)
    this.AnalyzerLoadFailed.Invoke(this, new AnalyzerLoadFailureEventArgs(AnalyzerLoadFailureEventArgs.FailureErrorCode.NoAnalyzers, null, null));

参见 C# 6.0 – 空传播运算符，您也可以在此处

我也曾经在 c# 6 中写过这个即将推出的特性 <强>这里

i also once wrote about this upcoming feature in c# 6 here

推荐阅读
热点文章

Copyright 2018 51数据库(www.51sjk.com)

软件
前端设计
程序设计
Java相关