我如何修复这个ArgumentNullException在int.Parse

本文关键字：int Parse ArgumentNullException 何修复 | 更新日期: 2023-09-27 18:05:19

这是。cs文件在Mono中运行良好:

using System;
public class HelloWorld
{
    static public void Main ()
    {
    Console.WriteLine("Enter a number");
    int UserNumber = int.Parse(Console.ReadLine());
    Console.WriteLine("Your number is: " + UserNumber);
    }
}

我在Xamarin中打开了这个Test.cs文件，它正常工作。然后我选择'Run'> 'Start Without Debugging'，这些错误弹出在显示面板:

Enter a number
Unhandled Exception:
System.ArgumentNullException: Argument cannot be null.
Parameter name: String
  at System.Number.StringToNumber (System.String str, NumberStyles options, System.NumberBuffer& number, System.Globalization.NumberFormatInfo info, Boolean parseDecimal) [0x00054] in /private/tmp/source-mono-mac-4.0.0-branch-c5sr2/bockbuild-mono-4.0.0-branch/profiles/mono-mac-xamarin/build-root/mono-4.0.2/external/referencesource/mscorlib/system/number.cs:1084 
  at System.Number.ParseInt32 (System.String s, NumberStyles style, System.Globalization.NumberFormatInfo info) [0x00014] in /private/tmp/source-mono-mac-4.0.0-branch-c5sr2/bockbuild-mono-4.0.0-branch/profiles/mono-mac-xamarin/build-root/mono-4.0.2/external/referencesource/mscorlib/system/number.cs:755 
  at System.Int32.Parse (System.String s) [0x00000] in /private/tmp/source-mono-mac-4.0.0-branch-c5sr2/bockbuild-mono-4.0.0-branch/profiles/mono-mac-xamarin/build-root/mono-4.0.2/external/referencesource/mscorlib/system/int32.cs:140 
  at HelloWorld.Main () [0x0000b] in /Users/Yardenbourg/Desktop/Test.cs:9 
[ERROR] FATAL UNHANDLED EXCEPTION: System.ArgumentNullException: Argument cannot be null.
Parameter name: String
  at System.Number.StringToNumber (System.String str, NumberStyles options, System.NumberBuffer& number, System.Globalization.NumberFormatInfo info, Boolean parseDecimal) [0x00054] in /private/tmp/source-mono-mac-4.0.0-branch-c5sr2/bockbuild-mono-4.0.0-branch/profiles/mono-mac-xamarin/build-root/mono-4.0.2/external/referencesource/mscorlib/system/number.cs:1084 
  at System.Number.ParseInt32 (System.String s, NumberStyles style, System.Globalization.NumberFormatInfo info) [0x00014] in /private/tmp/source-mono-mac-4.0.0-branch-c5sr2/bockbuild-mono-4.0.0-branch/profiles/mono-mac-xamarin/build-root/mono-4.0.2/external/referencesource/mscorlib/system/number.cs:755 
  at System.Int32.Parse (System.String s) [0x00000] in /private/tmp/source-mono-mac-4.0.0-branch-c5sr2/bockbuild-mono-4.0.0-branch/profiles/mono-mac-xamarin/build-root/mono-4.0.2/external/referencesource/mscorlib/system/int32.cs:140 
  at HelloWorld.Main () [0x0000b] in /Users/Yardenbourg/Desktop/Test.cs:9 
The application was terminated by a signal: SIGHUP
我不知道这里的问题是什么。会不会和这条线有关?
int UserNumber = int.Parse(Console.ReadLine());

我如何修复这个ArgumentNullException在int.Parse

读取堆栈跟踪，它说Parse的方法传递了一个null参数，但它不能为null。尝试将读取行和解析行分开，然后确保该行不为null或空。

public class HelloWorld
{
    static public void Main ()
    {
    Console.WriteLine("Enter a number");
    String input = Console.ReadLine();
    int UserNumber = 0;
    if(input != null && input != "")
    {
        UserNumber = int.Parse(input);
    }
    Console.WriteLine("Your number is: " + UserNumber);
    }
}

像这样分割代码使代码更容易阅读和调试。

我打赌你使用的是C# -> Mac -> Xamarin.Mac项目。默认情况下，这些程序不使用交互式控制台，当您调用Console.ReadLine()时，您将尝试使用交互式控制台。

尝试创造一个新的解决方案;选择C# -> Console Project以使交互式控制台工作

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