[ale] debugging FORTRAN

[Eric Z. Ayers]

Just a quick perusal from the man pages show that g77 works the same
as gcc - you must add the -g flag to the command line when you compile 
your programs if you want debugging symbols in your program.  GDB
won't do much without them.  Try recompiling your code with 

g77 -g <sourcefile> -o <output file>

and then run GDB on your file:

$ gdb <output file>

(gdb) break main
(gdb) run <command-line arguments>

Use 'next' to step from one line to the next
'list' to look at the current line of source code.

If you have a core dump

$ gdb <output file> <core file>

$ gdb mytest core

(gdb) list    # will show you the code around where you crashed
(gdb) where   # will show a backtrace of all the subroutines


Hope that helped.
-Eric. 


Lisa Chiang writes:
 > ALE'rs:
 > 
 > I have some questions about gdb and FORTRAN.  Since g77 seems to be a FORTRAN
 > to C converter (right?), how do you get gdb to debug FORTRAN natively? I
 > downloaded the gdb manual and I must admit that I'm confused.
 > 
 > For example, I tried "show symbols" on my FORTRAN executable and all I see are
 > C symbols.  I seems that I can't load a source FORTRAN file and debug it like
 > you would a C program.
 > 
 > At this point I'm porting a large VMS VAX FORTRAN code to g77 but if I can't get
 > gdb to work with FORTRAN, I may just have to rewrite it in C which will take
 > some time.  Any suggestions? Thanks.
 > 
 > 
 >  --
 > Lisa Chiang
 > gt6492d at gatech.campuscwix.net
 > Georgia Institute of Technology