blocks|key|829986|text|Visual+Studio中的F#交互控制台不支持读取输入，因此无法从控制台请求输入。如果您以交互方式运行代码，则始终可以在编辑器中输入输入，因此最好的解决方法是在运行代码之前输入输入的开头绑定let。您可以使用#if来支持这两种场景：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|829987|#if+INTERACTIVE
//+TODO:+Enter+input+here+when+running+in+F#+Interactive
let+input+=+"42"
#endif

try+
++++#if+INTERACTIVE
++++Some(int32+input)
++++#else
++++let+x+=+System.Console.ReadLine();+
++++Some(int32(x))+
++++#endif
with+
++++%7C+:?+System.FormatException+->+
++++++++printfn+"Invalid+number!"+
++++++++Some(0)+|code-block|syntax|javascript|829988|entityMap^0|2P|3|2Y|3|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

The F# Interactive console in Visual Studio does not support reading input, so there is no way to ask for an input from the console. If you're running code interactively, you can always enter the input in the editor, so the best workaround is to have <code>let</code> binding at the beginning where you enter the input before running your code. You can use <code>#if</code> to support both scenarios:

<pre><code>#if INTERACTIVE
// TODO: Enter input here when running in F# Interactive
let input = "42"
#endif

try 
 #if INTERACTIVE
 Some(int32 input)
 #else
 let x = System.Console.ReadLine(); 
 Some(int32(x)) 
 #endif
with 
 | :? System.FormatException -&gt; 
 printfn "Invalid number!" 
 Some(0) 
</code></pre>

blocks|key|3201558|text|如果您将F#+interactive作为自己的进程打开(通过直接运行fsi.exe，代码就可以正常工作--下面是我的遭遇：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3201559|>+printfn+"Enter+a+number:"
-+let+r+=
-+++++try
-++++++++let+x+=+System.Console.ReadLine();
-++++++++Some(int32(x))
-+++++with
-++++++++%7C+:?+System.FormatException+->+printfn+"Invalid+number!"
-+++++++++++++++++++++++++++++++++++++++Some(0)
-+;;
Enter+a+number:
5

val+r+:+int32+option+=+Some+5|code-block|syntax|javascript|3201560|entityMap^0|Y|7|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

If you open F# interactive as its own process (by directly running <code>fsi.exe</code>, the code works fine - here is what happened to me:

<pre><code>&gt; printfn "Enter a number:"
- let r =
- try
- let x = System.Console.ReadLine();
- Some(int32(x))
- with
- | :? System.FormatException -&gt; printfn "Invalid number!"
- Some(0)
- ;;
Enter a number:
5

val r : int32 option = Some 5
</code></pre>

blocks|key|830024|text|试试下面，它在我的机器上运行良好(VS+2013，F#+3.1+12.0.21005.1)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|830025|let+inputTest+i+=+
++++printfn+"iter+-+%25d"+i
++++let+input+=+System.Console.ReadLine()
++++printfn+"%25s"+input
++++System.Console.ReadLine()+%7C>+ignore

List.iter+inputTest+[1..3]|code-block|syntax|javascript|830026|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Try below, it works fine on my machine (VS 2013, F# 3.1 12.0.21005.1)

<pre><code>let inputTest i = 
 printfn "iter - %d" i
 let input = System.Console.ReadLine()
 printfn "%s" input
 System.Console.ReadLine() |&gt; ignore

List.iter inputTest [1..3]
</code></pre>

blocks|key|3201639|text|在Visual+Studio+for+Mac+Community+7.4+(build+1033)中，我在编译和运行源文件时也遇到了这个问题，而不是脚本。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3201640|如果我使用集成控制台(它出现在output窗口旁边)，我无法使用System.Console.ReadLine()读取输入。|3201641|当我切换到外部控制台时，通过选中默认运行配置(+->+->+Options+->+Run:Configurations:+Default+)中的'Run+on+external+console‘复选框，我能够读取输入。|3201642|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

In Visual Studio for Mac Community, 7.4 (build 1033), I also ran into this problem when compiling and running source files, not scripts.

If I use the integrated console (it appears next to the output window), I cannot read input using System.Console.ReadLine(). 

When I change to the external console, by checking the 'Run on external console' checkbox in the Default Run Configuration (Project -> Options -> Run:Configurations:Default), I am able to read input.

So I am trying to do something simple:

<pre><code> printfn "Enter a number:"
 try
 let x = System.Console.ReadLine();
 Some(int32(x))
 with
 | :? System.FormatException -&gt; printfn "Invalid number!"
 Some(0)
</code></pre>

I want to print the message, then get the user to input a number, and try to convert it to an int and return it.

If I just compile the code (by typing fsc a3.fs on the command line), it works fine. It pauses, waits for input, then returns Some(int).

If I copy and paste the code into the FSI on the command line, it works great. 

But when I am in visual studio, and I run the code in the FSI (highlight + alt+enter), it just goes right over the input part and the exception is thrown (and caught).

Here is the output when I run in the FSI (in visual studio):

<pre><code>Enter a number:
Invalid number!
0
</code></pre>

As you can see, It doesnt ever actually pause and wait for me to enter input.

Anyone know how to make this work?

Thanks!

How to read user input using f# interactive in visual studio?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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所以我试着做一些简单的事情： printfn "Enter a number:"    try       let x = System.Console.ReadLine();       Some(int32(x))    with       | :? System.FormatException -> print...

问如何在visual studio中使用f# interactive读取用户输入？
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问如何在visual studio中使用f# interactive读取用户输入？EN