1. Debuggers

2. Using a debugger
A primitive way of debugging is to insert print statements.

3. Using a debugger
A primitive way of debugging is to insert print statements.
That’s OK but a debugger is much more powerful.
It’s a program that watches and controls another program as it runs!

4. Using a debugger
A primitive way of debugging is to insert print statements.
That’s OK but a debugger is much more powerful.
It’s a program that watches and controls another program as it runs!
It allows us to execute our code one line at a time.
It allows us to set breakpoints (stop points) in our code.
We can even examine and change the contents of variables as our program runs!

5. jgrasp

6. Setting a breakpoint (jGRASP)

7. Breakpoint is now set (jGRASP)

8. Start the debugger (jGRASP)
Build -> Debug
The program then runs and stops at our first breakpoint.

9. jGRASP step over step in variables (r-click to change value) step out
next line to be executed
end debugging

10. VC++

11. Setting a breakpoint (VC++)

12. Starting the debugger (VC++)

13. Watch variables (VC++)

14. VC++ debugging options

15. gdb

16. Debugging with gdb (Unix/Linux)
Direct compiler to include debugging information with –g (ex. g++ -g test.cpp)
Run the debugger and indicate program to debug (ex. gdb ./a.out)

17. Setting a breakpoint (gdb) in main and start running

18. Print and set (change) var

19. List source code

20. Useful gdb commands b main set breakpoint in func main
b 10 set breakpoint at line #10
cont continue
del break delete all breakpoints
l (ell) list source code lines
l <func> (ell) list source code lines for <func>
n next (like step over)
p <var> print contents of variable
quit end execution
run start running program
s step (like step into)
set <var>=value change var