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From: gpwrmdh@gp.co.nz
Newsgroups: comp.os.vms,comp.lang.fortran
Subject: Re: Checking a string for an integer
Message-ID: <1991Apr2.101544.1490@gp.co.nz>
Date: 1 Apr 91 22:15:44 GMT
References: <1991Apr1.104227.243@biivax.dp.beckman.com>
Organization: GP Print Ltd, Wellington, New Zealand
Lines: 66

In article <1991Apr1.104227.243@biivax.dp.beckman.com>, dsroberts@biivax.dp.beckman.com writes:
> I would like to take a 3 byte string and find out if it contains only ascii
> digits for number or if letters were entered.  On VMS, the DCL command would be
> 
> result = f$integer (string)
> 
> which would put the numeric equivalent in result, or return an error.  I don't
> find an obvious way to do this in FORTRAN.  Any suggestions?  I am not averse
> to a VMS system service, btw.

Here is a simple example program:

	program test
	implicit none
	
	character*3 in
	integer out, status

	write (*, fmt='(''$number: '')')

	read (*, fmt='(a3)') in
	read (unit=in, fmt='(i3)', iostat=status) out

	if (status .eq. 0) then
	    type *, 'Converted ok'
	    type *, 'Number = ', out
	    type *, 'Returned status = ', status
	    if (out .gt. 254) type *, 'Number too big'
	else
	    type *, 'Error converting number'
	    type *, 'Status = ', status
	end if

	end

Basically, you use the READ statement to convert the string to internal 
format, and check the returned status - success returns a 0. You will 
probably want more error checking than I have put in the above.

The error code returned for invalid numbers is code 64, meaning "input 
conversion error".

> 
> And, just in case I am missing some better alternative, what I am trying to
> accomplish is to find out if this 3 byte string contains a number in a valid
> range (in this case 1-254) or not.  The only requirement is that I start with a
> 3-byte string.  Pointers to the appropriate pages in the VMS FORTRAN manuals
> would be appreciated :-)

Section 4.2.3.2 of the Fortran User's manual (V5.0) has a little about
internal i/o, and also section 7.2.4 of the Fortran Reference Manual.

> -- 
> ---------------------------------------------------------------------------
>    Don Roberts                   Internet:  dsroberts@beckman.com
>    Beckman Instruments, Inc.     Yellnet:   714/961-3029
>    2500 Harbor Bl. Mailstop X-12 FAX:       714/961-3351
>    Fullerton, CA  92634          Disclaimer:  Always
> ---------------------------------------------------------------------------
-- 
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Martin D. Hunt			
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