How do I redirect output from the Visual Studio debugger?

Question

In Visual Studio 2008, I can specify a message to be printed when a breakpoint is hit (by right-clicking the breakpoint and choosing 'When Hit...'). When the program is run, these messages appear in the Output Window. I would like to know, is there any way to redirect them to a file?

Specifying >file.txt as a command argument to the program does not work: this redirects the program's output, but not the debugger's.

(FWIW the behaviour I wish to achieve is to get the debugger to repeatedly print a variable's value to a file, rather than peppering my code with printf/cout statements.)

Answer 1

Under Windows 2000, XP, Server 2003 and Vista DebugView will capture:

• Win32 OutputDebugString
• Kernel-mode DbgPrint
• All kernel-mode variants of DbgPrint implemented in Windows XP and Server 2003

DebugView allows you to filter the output, add time stamps and log to file.

The catch is, you need to run without attaching to the debugger, for DbgView to capture the output. (Use Ctrl+F5)

Answer 2

1. Set the option Redirect all Output Window text to the Immediate Window. We find it in Tools → Options → Debugging → General (fifth to last item).

2. Open the Immediate Window: Ctrl + Alt + I or Debug → Windows → Immediate Window

3. Enter a command like the following in the Immediate window:

   > Tools.LogCommandWindowOutput /on C:\mylogfile.txt
   

4. To stop writing to the file, enter the following command in the Immediate window:

   > Tools.LogCommandWindowOutput /off