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PaulHolden · Joined: 08 Jan 2018 Posts: 6

Is there a "correct" way to wrap the Centre@ function in another function using Fortran 90/95? Centre@ returns a string of length determined by the assignment statement which cannot easily be replicated in code (at least I can't find an obvious way). Many years ago I vaguely remember a newsgroup question on a similar topic in which one of the elder statesmen of Fortran said that this sort of this was not within the scope (or desirability) of the F90 standard.

Before anyone asks, I am trying to create a portability wrapper so the main code can be compiled in various compilers including FTN95.

LitusSaxonicum · Posted: Mon Jan 08, 2018 3:39 pm Post subject:

One lives and learns - I never knew such a function existed.

Surely it is a matter of positioning the input string STRING in a character variable of length LW (as in FTN95.CHM) by (LW-LEN_TRIM(STRING))/2 from the start of the output string? (and therefore not difficult).

Eddie

PaulLaidler · Posted: Mon Jan 08, 2018 4:01 pm Post subject:

Also I suspect that the length of the result is determined by the declaration of CENTRE@ and not by an assignment statement. For example

PaulHolden · Joined: 08 Jan 2018 Posts: 6

PaulLaidler · Posted: Mon Jan 08, 2018 5:49 pm Post subject:

I am assuming that somewhere in your code there is a declaration of the form

PaulHolden · Joined: 08 Jan 2018 Posts: 6

PaulLaidler · Posted: Mon Jan 08, 2018 6:19 pm Post subject:

Perhaps the easiest solution is to use Eddie's approach.

PaulHolden · Joined: 08 Jan 2018 Posts: 6

wahorger · Joined: 13 Oct 2014 Posts: 1257 Location: Morrison, CO, USA

Is the single statement use of a function *REQUIRED* to happen, or can you use a subroutine call?

Something of the form of:

PaulHolden · Joined: 08 Jan 2018 Posts: 6

Thanks wahorger. The subroutine isn't as convenient as a function but it seems to be the only solution.

PaulHolden · Joined: 08 Jan 2018 Posts: 6

LitusSaxonicum · Posted: Sun Jan 14, 2018 4:53 pm Post subject:

If I am right (and I concede that it is about 20 years since I last worked with Assembler, so I could be wrong), then all a FUNCTION returns is the address to its result on the stack. Moreover, the result is 'forgotten' immediately after the assignment or WRITE in which the function is invoked when the stack is cleaned up.

Hence, so long as the return address is mangled to point to the string of length LW with the input STRING centered in it, then that sequence of characters ought to be picked up in the calling routine and copied (or used) for that one time. It doesn't matter where in RAM that temporary copy resides, surely, and it could reside somewhere where it was ephemeral, i.e. allocated dynamically, if you so wish.

I assume that FTN95 reserves a long enough contiguous sequence of bytes at compilation by finding the longest declaration of the length of CENTRE@ (viz. FTN95.CHM's example call), the address of which is known to it, to Paul, and all the other folk at Silverfrost who understand such things, especially if there is a statically allocated sequence just reserved for it somewhere.

Of course the best answer is not to bother with those other compilers, and stick to FTN95, but then my view is that FTN95 is the best in every respect, and others are free to differ.

Eddie

mecej4 · Joined: 31 Oct 2006 Posts: 1899

Paul Holden:

I am not sure about what you require, but how about something like this?

mecej4 · Joined: 31 Oct 2006 Posts: 1899

KennyT · Joined: 02 Aug 2005 Posts: 318

When using DRAW_CHARACTERS@, with a proportional font, is there a way to determine the size in pixels of the box that contains the text, such that right/centre justification can be calculated for hardcopy...

K