Watching Local Variables That Are Also Globally Declared

 Last reviewed: November 2, 1995
Article ID: Q98288
The information in this article applies to:
  • Microsoft Win32 Software Development Kit (SDK) versions 3.1, 3.5. 3.51, and 4.0

SUMMARY

Consider debugging the following program in WinDbg: 

   int x = 1;
   int y = 2;

   void main()
   {
      int x = 2;
      x++;
      y++;
   }
Notice that there is a global variable x and a local variable x.

Before you step into main, if you set watchpoints on x and y, the Watch window will display a value for y but for x will say "Expression cannot be evaluated." To see the value for x, use ::x and x will evaluate to the local x in main once you've stepped into main.

MORE INFORMATION

When debugging an application, the X86 C++ evaluator is loaded. Given this, you can use the scope resolution operator in a watch statement to view a hidden global variable. Without the use of the scope resolution operator, there is no way (short of watching it in a memory window) to watch a hidden global variable.

Additional reference words: 3.10 3.50 4.00 95
KBCategory: kbtool
KBSubcategory: TlsWindbg

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Last reviewed: November 2, 1995
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