在ASP.NET应用程序中启用C#7

本文介绍了在ASP.NET应用程序中启用C#7的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我刚刚开始在Visual Studio 2017中处理旧的解决方案.只需在旧的IDE中打开解决方案即可正常工作. 现在，c#应用程序项目默认为c#7.0编译器.通过这些项目的属性页(编译/高级)，可以轻松选择编译器的目标语言版本，默认为最新版本.

I just started working on my old solution in Visual Studio 2017. Just opening the solution in the old IDE worked seamlessly. The c# application projects now default to the c# 7.0 compiler. The property pages of those project (compilation/advanced) let easily chose the targeted language version of the compiler, defaulting to the latest.

虽然我找不到在 asp Web项目中启用c#7.0的方法. 如果我写如下语句:

I cannot find a way to enable c# 7.0 in the asp web projects though. If I write a statement such as:

if (int.TryParse("1", out int myInt)) { ... }

IDE警告我说我需要使用该语言的7+版本.

the IDE warns me saying that I need to use version 7+ of the language.

我对该主题的研究表明，我应该在web.config文件的system.codedom编译器区域中定位特定的c#版本，以便定位最新的Roslyn版本.

My research on this topic shows I should target the specific c# version in the system.codedom compilers area of the web.config file, so to target the newest Roslyn version.

我现在拥有的是:

<system.codedom> <compilers> <compiler language="c#;cs;csharp" extension=".cs" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.3.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4" compilerOptions="/langversion:6 /nowarn:1659;1699;1701"/>

以c#6为目标.如果已经下载了最新的带有nuget的Roslyn，则c#7的正确设置是什么?

which targets c# 6. What are the correct settings for c# 7, provided that I have already downloaded the latest Roslyn with nuget?

更新 这是一个网络项目可用的 Compile 选项的屏幕截图(它是意大利语VS2017，但应该很容易理解).无法在此处选择目标C#版本.

Update Here is a screenshot of the available Compile options for a web project (it is Italian VS2017 but it should be easy to understand). No possibility to select the targeted c# version there.

推荐答案

在网站的NuGet窗口中:

In website's NuGet window:

卸载Microsoft.CodeDom.Providers.DotNetCompilerPlatform

重新安装

在web.config中， 下:system.codedom > compilers > compiler， 将compilerOptions ="/langversion: 6更改为7

Uninstall Microsoft.CodeDom.Providers.DotNetCompilerPlatform

Re-install it

In web.config, under: system.codedom > compilers > compiler, change compilerOptions="/langversion:6 to 7