C and C++ SoftBench User's Guide

Using SoftBench Debugger

Setting and Using Watchpoints

Chapter 7 199

Setting and Using Watchpoints

Watchpoints allow you to monitor the value of an expression, or the

contents of a range of memory, while your program executes. SoftBench

Debugger checks the value (as often as speciﬁed in the watchpoint

deﬁnition), notiﬁes you when it changes, and pauses your program.

This can be extremely useful when searching for "mystery" errors. For

example, suppose at some unknown time your program corrupts an

important area in memory. Without watchpoints, it would be very

difﬁcult to determine exactly when the corruption occurred. Using

watchpoints, you can quickly ﬁnd when the corruption happens, which

gives you a good idea of what caused it.

When you create a watchpoint, you specify the expression or address

range to monitor, and an option to specify "granularity". Granularity

speciﬁes how often the value of interest should be monitored:

• At every procedure entry

• At every procedure exit

• At the entry and exit of every procedure

• Every statement

• Every assembly instruction

• whenever the program stops and returns control to the debugger

The Watchpoint dialog setting defaults to "Stop". This default allows you

to monitor the current values of some data items when debugging a

program.

Be certain you specify an appropriate granularity. If you want SoftBench

Debugger to watch a variable while your program runs, you should not

have the "❍ Stop" radio button active in the "Set At" area. This setting

only checks your watchpoints when your program reaches a breakpoint

or is interrupted for another reason. You should specify a procedure- or

statement-level granularity so SoftBench Debugger checks the variable

while your program runs. You can also use the "❍ Modification" radio

button to identify when an address or variable is unexpectedly being

changed. This button issues a default DDE watchpoint command on the

contents of the "()" input box. This same feature can also be accessed

from the menu under "Watch: Set at Modification".