Re: GDB

[Peter Willis]

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.

ie:

ddd <PROGRAM_FILE_PATH_AND_NAME_TO_DEBUG>


EXAMPLE:

ddd  C:\my_files\my_program_to_debug.exe

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

C:\\my_files\\my_program_to_debug.exe

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  <FILE_NAME>:<LINE_NUMBER>

EXAMPLE:

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.

P

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
> understand
>
> 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
>
> misleading.
>
> 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,
>
> Christian