Asp Net Cookbook 1002004 [Electronic resources] نسخه متنی

Recipe 10.7 Using a Breakpoint to Stop Execution of an Application When a Condition Is Met

10.7.1 Problem

You have some fairly complicated code
that is having a problem after many
iterations, and you need an easy way to stop execution when the
conditions are met.

10.7.2 Solution

Set a conditional breakpoint using an expression in the Visual Studio
debugger. The value of the expression will determine whether program
execution breaks when the breakpoint is hit.

To set a conditional breakpoint in the Visual Studio debugger:

1. Set a breakpoint in the usual fashion by clicking in the gray border
   to the left of the line where you want execution to break.

2. Right-click the breakpoint and select the Breakpoint Properties
   command from the menu.

3. Use the Breakpoint Properties dialog box to set the conditions for
   the break, as shown in Figure 10-5. Typically,
   you'll use the Function tab, select the Breakpoints
   button, and set a conditional expression like any of these:

   
   counter = 5000
   i=100 AND j=150
   message.Length > 0
   counter == 5000
   i==100 && j==150
   message.Length > 0

When you run the program, execution will break at the location when
the expression is true or has changed, depending on the option
you've chosen in the dialog box.

Figure 10-5. Setting a conditional breakpoint in Visual Studio

10.7.3 Discussion

You can view the contents of the Visual Studio Locals window to
verify the values of the variables involved in the expression. Access
the Locals window by selecting the Debug Windows
Locals command; the Locals window is accessible only when
the VS.NET Debugger is active.

Another approach is to set a hit count within the Function tab. The
hit count lets you specify how many times the breakpoint is hit
before the debugger enters break mode. For example, you might choose
to break when the hit count is equal to 100. The debugger will break
only when the hit count reaches the target number.

10.7.4 See Also

All the rules for setting breakpoint expressions are available from
Visual Studio Help under the "Expressions in the
Debugger" topic, which is accessible from the
Breakpoint Properties dialog box (the expression evaluator accepts
most expressions written in Visual Basic or C#).