Last year I spent some time debugging Qt C++11 code using the GNU Debugger GDB https://www.gnu.org/software/gdb/ (as well as profiling with Valgrind http://valgrind.org/ ).

To skill up on this, I read the "Art of Debugging with GDB, DDD & Eclipse" http://www.amazon.com/The-Art-Debugging-GDB-Eclipse/dp/1593271743 (from the excellent as always No-Starch Press). I got to know its command syntax - here are my notes, for the next time I dive back into C++ !

•     run p a       - execute a program p under debug. can pass in args a

Breakpoints:

•     break n/f   - break at line n / at function f
•     tbreak n     - temporary breakpoint - break once
•     condition b (c)  - specify condition for breakpoint b
•     break b if (c)  - combine break & condition into 1 line
•     catch e       - catchpoint for event e
•     info break   - list breakpoints + #times they have been hit
•     delete n     - delete breakpoint n
•     clear f     - delete breakpoint at function f
•     disable b   - disable breakpoints
•     enable b     - enable breakpoints
•     enable once b
•     commands b   - execute command list when a breakpoint is hit

•     next         - step over
•     step         - step in
•     finish       - step out
•     until       - step out of a recursive function or a loop
•     continue     - resume
•     jump n       - move the program counter to a different code location

•     define m     - define a macro
•     end         - end command list / macro definition
•     show user   - show list of macros

•     list f       - list the contents of a function in the code pane --> switch between source files to give it focus
•     Ctrl XA       - toggle TUI mode
•     Ctrl P / N   - switch to previous / next source file
•     i           - switch focus to command pane
•     esc         - switch focus to code pane
•     j/k         - down / up navigation in source pane
•     /           - search in source pane

•     disassemble - show machine code
•     p/x         - print in hex format. other formats: c, s , f (char, string, float)
•     $pc         - current location
•     print x     - print the value of a variable
•     printf       - formatted print
•     display *x   - automatically print an object whenever a breakpoint is hit
•     p *a@n     - print out n elements of dynamic array a
•     ptype o     - print out a C++ object's class definition
•     info locals - print out local vars
•     examine     - examine the memory at a particular address
•     enable d     - enable a display
•     disable d   - disable a display
•     delete d     - delete a display
•     info args   - print out args
•     p *$1       - print out something from the value history
•     p errno     - print error code
•     strace c     - print trace - shows system calls for a command
•     info threads        - determine what each thread is doing. (after this, bt).
•     x/4w $esp   - examine memory (x) - eg 4 words (4w) at the stack pointer ($esp)

•     call f       - call a function - eg from a breakpoint command list
•     set x=v     - set a variable x to a value v
•     set args     - for next run
•     set $q = p   - create a debugger variable that points to some memory address
•     thread t     - switch to thread t
•     break b thread t if (c) - combo

•     ENTER       - repeat last command
•     handle       - dont break on signals
•     help
•     quit