display character strings in fortran

display character strings in fortran

[kamaraju kusumanchi]

Consider the following code. (This is a reduced version of a large
code that I am working with.)

$cat char_string.f90
program string_size
  implicit none
  character (len=20) :: first_name
  write(first_name, *) 'kamaraju'
  write(*,*) first_name
end program string_size

The program compiles and runs fine.

$gfortran -g char_string.f90
$./a.out
  kamaraju

However, when debugged, the character strings are not displayed properly.


$gdb ./a.out
Using host libthread_db library "/lib/i686/cmov/libthread_db.so.1".
(gdb) b char_string.f90:5
Breakpoint 1 at 0x8048620: file char_string.f90, line 5.
(gdb) r
Starting program: /home/rajulocal/work/fortran/a.out

Breakpoint 1, string_size () at char_string.f90:5
5         write(*,*) first_name
Current language:  auto; currently fortran
(gdb) p first_name
$1 = (32 ' ', 107 'k', 97 'a', 109 'm', 97 'a', 114 'r', 97 'a', 106
'j', 117 'u', 32 ' ', 32 ' ', 32 ' ', 32 ' ', 32 ' ', 32 ' ', 32 ' ',
32 ' ', 32 ' ', 32 ' ', 32 ' ')
(gdb) quit
The program is running.  Exit anyway? (y or n) y



I am using a Debian Etch machine running

$gfortran -v
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian
4.3.2-1.1' --with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr
--enable-shared --with-system-zlib --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --enable-nls
--with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3
--enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc
--enable-mpfr --enable-targets=all --enable-cld
--enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu
--target=i486-linux-gnu
Thread model: posix
gcc version 4.3.2 (Debian 4.3.2-1.1)

$gdb -v
GNU gdb 6.4.90-debian
Copyright (C) 2006 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i486-linux-gnu".



Is this a bug in gdb or gfortran? I appreciate if you could fix it.

thanks
raju

Re: display character strings in fortran

[Arjen Markus]

With the p command in gdb you print via the debugger - that is
something completely
different than writing/printing a variable's value in the Fortran
program. What you see
is simply the debugger's way of looking at (Fortran) strings.

Regards,

Arjen

Re: display character strings in fortran

[kamaraju kusumanchi]

On Wed, Jun 10, 2009 at 7:56 AM, Tobias Burnus<burnus@net-b.de> wrote:
> kamaraju kusumanchi wrote:
>> However, when debugged, the character strings are not displayed properly.
>> [...]
>> (gdb) p first_name
>> $1 = (32 ' ', 107 'k', 97 'a', 109 'm', 97 'a', 114 'r', 97 'a', 106
>> 'j', 117 'u', 32 ' ', 32 ' ', 32 ' ', 32 ' ', 32 ' ', 32 ' ', 32 ' ',
>> 32 ' ', 32 ' ', 32 ' ', 32 ' ')
>> [...]
>> gcc version 4.3.2 (Debian 4.3.2-1.1)
>
>> Is this a bug in gdb or gfortran? I appreciate if you could fix it.
>
> The GCC bug was fixed about half a year ago. Please use GCC 4.4.0 (which
> was released April 21, 2009) or later. Using GCC 4.4.x, one gets:
>
> (gdb) p first_name
> $1 = ' kamaraju', ' ' <repeats 11 times>
>
> Tobias
>


Upgraded my gfortran to

$gfortran-4.4 -v
Using built-in specs.
Target: i486-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian
4.4.0-5' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr
--enable-shared --enable-multiarch --with-system-zlib
--libexecdir=/usr/lib --without-included-gettext
--enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4
--program-suffix=-4.4 --enable-nls --enable-clocale=gnu
--enable-libstdcxx-debug --enable-mpfr --enable-objc-gc
--enable-targets=all --with-arch-32=i486 --with-tune=generic
--enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu
--target=i486-linux-gnu
Thread model: posix
gcc version 4.4.0 (Debian 4.4.0-5)


Now it works as intended.

thanks for the quick replies
raju

Re: display character strings in fortran

[Tobias Burnus]

kamaraju kusumanchi wrote:
> However, when debugged, the character strings are not displayed properly.
> [...]
> (gdb) p first_name
> $1 = (32 ' ', 107 'k', 97 'a', 109 'm', 97 'a', 114 'r', 97 'a', 106
> 'j', 117 'u', 32 ' ', 32 ' ', 32 ' ', 32 ' ', 32 ' ', 32 ' ', 32 ' ',
> 32 ' ', 32 ' ', 32 ' ', 32 ' ')
> [...]
> gcc version 4.3.2 (Debian 4.3.2-1.1)

> Is this a bug in gdb or gfortran? I appreciate if you could fix it.

The GCC bug was fixed about half a year ago. Please use GCC 4.4.0 (which
was released April 21, 2009) or later. Using GCC 4.4.x, one gets:

(gdb) p first_name
$1 = ' kamaraju', ' ' <repeats 11 times>

Tobias