433-252 - Lab 3 / Week 4: Debugging with GDB

Tasks

Debug the following programs:

• uniquecount
• concord
• Our dear friend fitn

Tips for debugging fitn:

• After you have debugged fitn, prove it by running your regression test suite from lab 2!
  You may find that these tests fail even though "data" passed! (data does not have good test coverage at all!)
  Try to make them all pass!
• Note: Not all of the expected output files are necessarily correct! Sometimes you'll find a bug in a test case itself. In that case, you should sensibly consider if the expected output is correct, and if not, fix it.
• As well as using gdb, compile fitn with bgcc, and make use of the bounds-checking errors.

Get them at:

/home/subjects/252/local/lab/lab03/*

GDB commands

• help
• help <command> - Little man page for any GDB command
• break <subroutine> - Set a breakpoint at the start of a function
• break <filename>:<linenum> - Set a breakpoint at a particular line of a source file
• run - Start execution
• c - Continue execution
• fin - Continue execution until the function exits
• s - Step a single line, may step into subroutines
• n - Step a single line, will step over subroutines
• l - Print program source listing
• p <variable> - Print the value of a variable or C expression
• q - Quit