FIX: Run-time Error 6 "Overflow When Compiled to Native Code"

• Microsoft Visual Basic Control Creation, Learning, Professional, and Enterprise Editions for Windows, version 5.0

SYMPTOMS

The following error may occur when the if expression uses Byte data type:

   "Run-time error '6'.  Overflow."

CAUSE

Visual Basic does not evaluate Byte data type correctly in the if expression when compiled to Native code with optimizations.

RESOLUTION

Install Visual Studio 97 Service Pack 2 (SP2). The problem can also be addressed by compiling to P-code, compiling to Native Code with no optimizations, or using a data type other than the byte data type in the if expression.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. This bug has been fixed in Visual Studio 97 Service Pack 2.

For more information on the Visual Studio 97 Service Pack 2, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q170365
   TITLE     : INFO: Visual Studio 97 Service Packs - What, Where, and Why

   ARTICLE-ID: Q171554
   TITLE     : INFO: Visual Basic 5.0 Fixes in Visual Studio 97
               Service Pack 2

MORE INFORMATION

The following code (known as the "Triangle Inequality") will run as expected in the Visual Basic IDE or compiled as P-code but will fail when compiled as a Native EXE file with optimizations.

Steps to Reproduce Behavior

1. Start a New Standard EXE project. Form1 is created by default.

2. In the General Declarations section of Form1, place the following code:

         Sub Checksides (a as Byte, b as Byte, c as Byte)
   
             If (c > a + b) or (a > b + c) or (b > a + c) then
                 MsgBox "Not a triangle"
             Else
                 MsgBox "Triangle"
             End If
   
         End Sub
   
   

3. In the Form_Load() event of Form1, place the following code:

         Private Sub Form_Load()
           CheckSides 1,1,1
           End
         End sub
   
   

4. Select Project Properties from the Project menu. Open the Compile tab and make sure the project is set to compile to Native Code with some sort of optimization selected, such as Optimize for fast code.

5. Select Make Project1.exe from the File Menu.

6. Execute the Project1.exe file.

Keywords          : vb5all VS97FixlistSP3 VS97FixlistSP2 VB5FixlistSP2
Version           : 5.0
Platform          : WINDOWS
Issue type        : kbbug
Solution Type     : kbfix kbservicepack