Using getarg in a Fortran program

Here's the man page on getarg:

NAME
     getarg, iargc - return Fortran command-line argument

SYNOPSIS
     subroutine getarg(i, c)
     character*N c
     integer*4 i

     integer*4 function iargc()
     integer j

     call getarg(i, c)
     j = iargc()

DESCRIPTION
     getarg returns the i-th command-line argument of the current process.

     iargc returns the index of the last argument.

          foo arg1 arg2 arg3

     getarg(2, c) would return the string ``arg2'' in the character variable
     c.

     iargc would return 3 as the value of the function call.

SEE ALSO
     getopt(3C).

NOTES
     The compiler expects the existence of a Fortran MAIN_ program when these
     functions are used.