start from command line with:

gdb

Include the file extention.

Commands:

Run	run the program
break filename.cpp:line_number	set breakpoint
break function_name	set breakpoint at start of function
continue	continue running after a breakpoint.
next	execute next line of code. If the line contains a function call, it is treated as a single line.
step	execute next line of code. If the line contains a function call, it is stepped into.
print i	display contents of variable
where	display function call stack
frame n	switch to call stack frame n. 0 is the current stack frame.
set args	to set command line arguements.

using gdb as the jit debugger:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AeDebug]
"UserDebuggerHotKey"=dword:00000000
"Debugger"="\"C:\\gdb\\bin\\gdb.exe\" -p %ld"



References:

• debugging-with-gdb
• Problem running GDB as JIT debugger on Windows XP