Breaking On Access

Related Topics:

Data Change Tracking	Breakpoints in C++ Classes
Breakpoints Window

You can set an On Access breakpoint to stop program execution when the contents of a variable or memory address is either read or written. On Access is a generalized version of On Modify that can detect accesses in the stack or in system calls.

To set an On Access breakpoint:

1. In the Debugging Window, choose Windows Breakpoints. Or, choose Execute Set Breakpoints.

2. If the Details pane of the Breakpoints window is not displayed, click the Add/Change Breakpoint button (the Add/Change Breakpoint button toggles to Hide Details).

3. Choose Event On Access. In the Event text box, type `r' 'to break on read access, 'w' to break on write access, or 'x' to break on execute memory accesses. You can type any combination of these three letters. Then type 'b' to break before the access or ''a' to break after the access. Finally, type the address you want to watch. For example:

rwa &var

wa &var + 40

4. If you are using a hexadecimal address or are using the address of a variable with an unknown type, enter the size of the memory area you want to watch, preceded by a comma. For example:

rb 0x1234, 4

5. Choose Action Stop.

6. Click Add.