You can manually enter Break mode in several ways:
If you aren’t sure what part of your code may be responsible for a problem,
but you see it when it happens, the ability to manually enter Break mode can be
handy. Because it is possible for so many Windows events to occur in rapid succession,
however, the few hundred milliseconds it takes for you to click your mouse or
press a key after you spot the problem may put you into a part of your code that
has nothing to do with the problem.
If you can localize your problem to some extent, you can also specify places
in your code at which to enter Break mode automatically:
-
Set a breakpoint
- Use the Stop command
You can toggle a breakpoint either from the Debug menu, as shown in Figure
18.7, or by pressing the F9 key. If the current line has no breakpoint set, F9
sets one; if the line already has a breakpoint, F9 turns it off. If you want to
remove all breakpoints from your project, you can either use the Debug menu to
do so or press Ctrl+Shift+F9. The color of the line in the VB code editor reflects
the status of any line with a breakpoint.
FIGURE 18.7 Setting a breakpoint from the Debug menu.
Once set, your program will enter Break mode the moment that it reaches the
line of code with the breakpoint. The program’s execution is suspended just
before that line of code executes.
You can also toggle individual breakpoints on or off by clicking in the bar
to the right of a line of code in Code window.
One problem with breakpoints is that they are not preserved between programming
sessions. That is, if you close a project after setting a breakpoint and then
reopen the project, your breakpoints will be gone. If you want to set a breakpoint
that persists between sessions, use the Stop command. The moment the Stop line
is reached in your code, the program enters Break mode.
WARNING - Avoiding Inadvertant Stop Commands: If
you’re worried about inadvertently leaving a Stop command in a project before
you deliver it to a client, remember that you can use a conditional compiler switch:
#Const DEBUGMODE = 1
#If DEBUGMODE Then
Stop
#End If
To be extra safe, set the value of DEBUGMODE on the
command line. Then you won’t have to worry about forgetting to remove the
definition of the compiler constant from your code either.
