Debugging with the GDB

GNU debugger(GDB) allows you to view the step by step execution of the program code. This proves of great help in executing complex programs(specially the ones involving recursion) to see the exact flow of control. How to debug using the gdb and a few options used are worth notable:
To debug a program with gdb , steps followed are
‘cc -g file.c’
gdb a.out. ….’a.out is your executable…’
You will see messages about the gdb version displayed on the terminal….
Now set the break point by
‘break main’
Use the ‘run’ command to start running the program.
The 3 commonly used options are ‘s’ ,’n’ ,’q’ with the gdb are…
‘s’ moves to the next line of code-it enters functions as well.
‘n’ moves to the next line of code as well but does not enter functions.
‘q’ is used to quit from the process.

A debugging process would be like this…

sunil:~/new# cc -g quicksort.c
sunil:~/new# gdb a.out
GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type “show copying”
and “show warranty” for details.
This GDB was configured as “i486-linux-gnu”…

(gdb) break main
Breakpoint 1 at 0x80483e5: file quicksort.c, line 7.
(gdb) run
Starting program: /root/new/a.out
Breakpoint 1, main () at quicksort.c:7
7 int left=0,right=4,i;

(gdb) s
8 int array[]={4,8,1,9,3};
…continue the process…

(gdb) q
Quits from the debugger


One response to this post.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s