GDB Debugging Programs




GDB Debugging Programs

 Gdb Debugging

Gdb Debugging

  • gcc -g myprogram.c
    • Compiles myprogram.c with the debugging option (-g). You still get an a.out, but it contains debugging information that lets you use variables and function names inside GDB, rather than raw memory locations (not fun).
  • gdb a.out
    • Opens GDB with file a.out, but does not run the program. You’ll see a prompt (gdb) - all examples are from this prompt.
  • r
  • r arg1 arg2
  • r < file1
    • Three ways to run “a.out”, loaded previously. You can run it directly (r), pass arguments (r arg1 arg2), or feed in a file. You will usually set breakpoints before running.
  • help
  • h breakpoints
    • Lists help topics (help) or gets help on a specific topic (h breakpoints).
  • q - Quit GDB

Stepping through Code

  • Stepping lets you trace the path of your program, and zero in on the code that is crashing or returning invalid input.
  • l
  • l 50
  • l my function
    • Lists 10 lines of source code for current line (l), a specific line (l 50), or for a function (l myfunction).
  • next
    • Runs the program until next line, then pauses. If the current line is a function, it executes the entire function, then pauses. next is good for walking through your code quickly.
  • step
    • Runs the next instruction, not line. If the current instruction is setting a variable, it is the same as next. If it’s a function, it will jump into the function, execute the first statement, then pause. step is good for diving into the details of your code.
  • finish
    • Finishes executing the current function, then pause (also called step out). Useful if you accidentally stepped into a function.

Breakpoints or Watchpoints

  • Breakpoints play an important role in debugging. They pause (break) a program when it reaches a certain point. You can examine and change variables and resume execution. This is helpful when some input failure occurs, or inputs are to be tested.
  • break 45
  • break myfunction
    • Sets a breakpoint at line 45, or at myfunction. The program will pause when it reaches the breakpoint.
  • watch x == 3
    • Sets a watchpoint, which pauses the program when a condition changes (when x == 3 changes). Watchpoints are great for certain inputs (myPtr != NULL) without having to break on every function call.
  • continue
    • Resumes execution after being paused by a breakpoint/watchpoint. The program will continue until it hits the next breakpoint/watchpoint.
  • delete N
    • Deletes breakpoint N (breakpoints are numbered when created).


Related Searches to GDB Debugging Programs

Adblocker detected! Please consider reading this notice.

We've detected that you are using AdBlock Plus or some other adblocking software which is preventing the page from fully loading.

We don't have any banner, Flash, animation, obnoxious sound, or popup ad. We do not implement these annoying types of ads!

We need money to operate the site, and almost all of it comes from our online advertising.

Please add wikitechy.com to your ad blocking whitelist or disable your adblocking software.

×