gdb is most effective when it is debugging a program that has debugging symbols linked in to it. With g++, this is accomplished using the -g command line argument. For even more information, the -ggdb switch can be used which includes debugging symbols which are specific to gdb. The makefile for this tutorial uses the -ggdb switch.

Preparing for the Interactive Part of the Tutorial The Basic Strategy The Main gdb Commands Invoking gdb The h (Help) Command a certain variable has a certain value. = -127, which is wrong. So, the location of the bug is now narrowed down to lines 101-150, and you will next check at line The Windows operating system doesn't have a built-in compiler. Therefore, Cygwin's version of g++, gdb (debugger) and make utility are used. We will install Cygwin (32-bit). This is done in 3 steps. Download and launch Cygwin Select and install packages Update PATH environment variables. A. Step 1: Download and launch Cygwin 1. Quitting GDB. quit [expression] q To exit GDB, use the quit command (abbreviated q), If you have been using GDB to control an attached process or device, you can release it with the detach command (see section Debugging an already-running process). Appendix E. Exit Codes With Special Meanings. Table E-1. Reserved Exit Codes. Exit Code Number Meaning Example 127 "command not found" illegal_command: Out of range exit values can result in unexpected exit codes. An exit value greater than 255 returns an exit code modulo 256. Stopping GDB quit exit GDB; also q or EOF (eg C-d) INTERRUPT (eg C-c) s null-terminated string i machine instructions disassem [addr] set param value set one of GDB's internal parameters show param display current setting of parameter Getting In and Out of GDB. This chapter discusses how to start GDB, and how to get out of it. The essentials are: type `gdb' to start GDB. To exit GDB, use the quit command (abbreviated q), or type an end-of-file character (usually C-d). June 29, 2009 edivad 127, debi