Converting character string to integer

Question

This is a follow up to my get_command_argument() question.

I'm reading a command line argument (arg) into a Fortran program. Then I want to store the value of arg as an integer. ichar() doesn't do the job.

This seems kind of basic, so clearly I'm doing something wrong. Any hints?

program test_get_command_argument
   integer :: i,j
   character(len=32) :: arg

   i = 0
   do
       call get_command_argument(i,arg)
       if (LEN_TRIM(arg) == 0) EXIT

       write (*,*) trim(arg)
       i = i + 1
   end do

   j = ichar(arg)


end program

@HighPerformanceMark doesn't command_argument_count() just return the number of arguments (I read that here), but I'd still like to work with the actual values of the arguments. — seb
– seb, Commented Nov 9, 2013 at 17:39

dwwork · Accepted Answer · 2013-11-09 15:59:12Z

1

You want to use the "internal files" capability. You should have a statement like read(arg,*) j. This will read the character variable arg as if it were a file and store the result into j.

answered Nov 9, 2013 at 15:59

dwwork

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4 Comments

seb Over a year ago

I just tried that. I put read(arg,'(I32)') j in the line after the call get_command_argument(), but at runtime I get the error: Bad integer for item 1 in list input

seb Over a year ago

got it, I am so used to argc and argv in C, that I totally missed the point that the first argument in get_command_argument() is actually the calling of the executable, duh. :-)

dwwork Over a year ago

Depends on what you mean by first argument...fortran is generally 1-based, not 0-based as C is. get_command_argument is the only exception I've seen, where 0 means the name of the program and 1 means the first argument sent to the program.

seb Over a year ago

yup, it's the only exception I've seen so far (in my very short fortran career) as well ;-)

High Performance Mark · Accepted Answer · 2013-11-09 18:24:48Z

1

This isn't an answer but an extended comment:

That's a bizarre way to loop over the command line arguments. What's wrong with the straightforward and obvious

do i = 1, command_argument_count()
   call get_command_argument(i,arg)
   ! do funky stuff    
end do

answered Nov 9, 2013 at 18:24

High Performance Mark

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1 Comment

seb Over a year ago

I agree. In found this example on the gcc.gnu.org website.

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