Variables as arguments in Fortran 77

[almeida]

Hi all...
I'm programming in Fortran 77 and i call a external program which receive 3 arguments. This arguments are variables of the fortran code. How can i pass this variables as arguments of the external program (or script), using the 'call system()' subroutine?


Thanks all...

[Rubberman]

Usually you have to dynamically build the command line with all the arguments and store that to a buffer which is passed in turn to the system() call. There are C language calls that will allow you to pass the argument list as a variable length argument list (execl) or an array of arguments (execv), but I don't know if you can call them from Fortran or not.

[drl]

Hi.

In keeping with a Fortran style, you can write to a Fortran character variable, and pass that to system:

#!/usr/bin/env bash

# @(#) s1	Demonstrate composed string to call system, Fortran.

echo
set +o nounset
LC_ALL=C ; LANG=C ; export LC_ALL LANG
echo "Environment: LC_ALL = $LC_ALL, LANG = $LANG"
echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version "=o" $(_eat $0 $1) gfortran
set -o nounset
echo

FILE=${1-t.f}

echo " Data file $FILE:"
cat $FILE

echo
echo " Results:"
gfortran -Wall -ffree-form $FILE
./a.out

exit 0

Producing:

% ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian GNU/Linux 5.0 
GNU bash 3.2.39
gfortran GNU Fortran (Debian 4.3.2-1.1) 4.3.2

 Data file t.f:
program main

integer mark
character*12 first, second
character*50 command

! As a literal string.

call system("echo 'Hello, world.'")

! As a string composed with a format to an "internal file".

first = " Hello, "
second = "world, and: "
mark = 99
write(command,'(a," ",a, " ",a," ",i2," ",a)') "echo '",first,second,mark,"'"
print*, "command ", command

call system(command)

end

 Results:
Hello, world.
 command echo '  Hello,      world, and:  99 '             
  Hello,      world, and:  99

Best wishes ... cheers, drl