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From: Peter Willis
Subject: Re: GDB
Date: Sun, 7 Feb 2016 10:49:23 -0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0

Hello Christian,

ddd is the debugging program. You are running ddd to open your executable file and step through it. ddd is a graphical user interface
front end for gdb debugger.  ddd is just passing control messages to
gdb and reading back the responses and displaying those in a window (or two).

Start up of ddd can be done via the command line.




ddd  C:\my_files\my_program_to_debug.exe

You may need to double up back slashes (? I cant know it all....):


The all assumes that you have compiled you application with the 'debug'
flag set :

gfortran -O0 -Og .......

ie: zero optimizations (-O0)   and debugging on (-Og)

Once you have ddd running, you will notice it has a console where you can type commands.

The '?' command will provide help.

To set a breakpoint enter :



break   my_fortran.f77:123

this will make a breakpoint at line 123 in file 'my_fortran.f77' (if it is ever run).

Hope that helps.


On 02/07/2016 03:12 AM, Christian Brembilla wrote:
Dear all,

I am really new in Fortran and GDB.  So sorry if I am asking you some
silly questions but I am stuck.

I want to explain to you every steps so there won´t be misleading.

I am running my program in F77 (Path=\F\G77\bin and library   path=
\F\g77\lib slatec)

I have also download GNU but I used G77 since I found some practical
examples on the net.

I am using the prompt from *windows.*

I believe that it can be useful a debugger with breakpoints so I can

where I am doing mistakes.

I download the GDB version gdb-7.10.1 but unfortunately I cannot understand

how can work. I mean in operative way. I looked at the pdf file
/gdb.pdf/ at the paragraph:

/Getting In and Out of GDB./

Unfortunately when I am typing gdb at the prompt I got the

/Gdb is not recognized as an internal or external command/

Do I have to type some path? Which one?

Could you please provide me a practical example?

For instance, I can explain you what I am doing with Fortran in this way
there are no doubts or


1.I made a program as the program below:

/File panel.for/

program panel

implicit none

real tin, Qn, tex

read*, n, e, dt, Tmax

do i = 2, Tmax

     do j = 1, e

       if (j .GT. 1)  then

       tsu =tex(i,j-1)

        end if …

… end do

end do

2.I compiled the program in the prompt by typing

C:\F\Panel>f2exe panel

C:\F\Panel> panel

 From here my program start correctly by asking me some values.

But when it solves the nested loop I got some odd values  -1IND

A debugger may be useful to understand what is going on.

Best regards,


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