简单的VB代码没有运行

Question

我做了VB.net中一个简单的例子，它编译并运行它：虽然它编译罚款

Public Class Application 
    Sub calc1() 
     Dim sq as Integer 
     'uncommenting this loop keeps it from compiling for some reason 
     'For i as Integer = 1 to 1000 
     ' sq = i*i 
     'End For 
     Console.WriteLine("calculated squares") 
    End Sub 

    Public Shared Sub Main() 
     Dim startTime as DateTime 
     Dim endTime as DateTime 
     System.Console.WriteLine("Hello world!") 
     startTime = Now 
     calc1() 
     endTime = Now 
     Console.WriteLine(endTime.Subtract(startTime).TotalSeconds.ToString("0.0000")) 

    End Sub 
End Class 

，它提供了运行时一个奇怪的错误：

Unhandled Exception: System.InvalidProgramException: Invalid IL code in ThreadTest.Application:Main(): IL_0018: ldarg.0 


[ERROR] FATAL UNHANDLED EXCEPTION: System.InvalidProgramException: Invalid IL code in ThreadTest.Application:Main(): IL_0018: ldarg.0 

Answer 1

Main function is required in file like as below : 

    Public Class Application 
      Public Shared Sub calc1() 
       Dim sq As Integer 
       'uncommenting this loop keeps it from compiling for some reason 
       'For i as Integer = 1 to 1000 
       ' sq = i*i 
       'End For 
       Console.WriteLine("calculated squares") 
      End Sub 
     End Class 

     Sub Main() 
      Dim startTime As DateTime 
      Dim endTime As DateTime 
      System.Console.WriteLine("Hello world!") 
      startTime = Now 
      Application.calc1() 
      endTime = Now 
      Console.WriteLine(endTime.Subtract(startTime).TotalSeconds.ToString("0.0000")) 
      Dim inputFromConsole As String 
      Dim outputToConsole As String 
      Console.WriteLine("Type in a sentence and hit Enter:") 
      inputFromConsole = Console.ReadLine() 
      Console.WriteLine(outputToConsole) 


     End Sub 

Answer 2

而不是End For在您的评论循环中，您需要使用Next。

其他部分是编译器错误，而不是你的错。 mono vb编译器仍然需要一些工作。如果我不得不猜测，我会说这里的问题要么是它看到你的方法没有真正的工作，并试图对Datetime.Now的两种用法做出不好的优化，或者它使用DateTime的错误重载。减去呼叫...但是，这些只是猜测。

但是，您应该做的是使用System.Diagnostics.Stopwatch类而不是日期时间值。

Answer 3

运行时错误是因为您正在从共享函数（Main）调用实例函数（calc1）。

较新版本的VBNC（Mono的VB编译器）的为您提供了这个错误：

test.vb (16,15) : error VBNC30369: Cannot refer to an instance member of a class from within a shared method or shared member initializer without an explicit instance of the class. 

该修正代码工作：

Public Class Application 
    Shared Sub calc1() 
     Dim sq as Integer 
     For i as Integer = 1 to 1000 
      sq = i*i 
     Next 
     Console.WriteLine("calculated squares") 
    End Sub 

    Public Shared Sub Main() 
     Dim startTime as DateTime 
     Dim endTime as DateTime 
     System.Console.WriteLine("Hello world!") 
     startTime = Now 
     calc1() 
     endTime = Now 
     Console.WriteLine(endTime.Subtract(startTime).TotalSeconds.ToString("0.0000")) 
    End Sub 
End Class