Path: utzoo!attcan!uunet!seismo!sundc!pitstop!sun!amdcad!ames!ncar!tank!oddjob!mimsy!chris
From: chris@mimsy.UUCP (Chris Torek)
Newsgroups: comp.lang.fortran
Subject: Re: i++, i+=1, i=i+1
Message-ID: <13583@mimsy.UUCP>
Date: 16 Sep 88 10:53:46 GMT
References: <13566@mimsy.UUCP> <3629@lanl.gov>
Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
Lines: 46

>In article <13566@mimsy.UUCP> I wrote a nice flowery description
showing exactly why I say `i += 1' is superiour to `i = i + 1', and
described it as follows:
>>... I, as a reader, would much rather see as an English description the
>>phrase `add 1 to i' than `evaluate i, evaluate the integer constant 1,
>>add the values together, and store the result in the location named by i'.
Likewise, I would rather see `i += 1' than `i = i + 1'.

In article <3629@lanl.gov> jlg@lanl.gov (Jim Giles) answers:
>My english description of 'i = i + 1' _is_ "add 1 to i".  the difference
>between that and 'i += 1' is purely textual.

Very well.  Let us remove the `**' operator from FORTRAN, replacing it
with the `POWER' intrinsic.  The difference is purely textual.

>...  In other words, as far as functionality goes, '+=" doesn't do a
>damn thing.

Actually, it does, although it would not in FORTRAN.  In C, given

	int *pickone() { static int a, b; return (rand()&1 ? &a : &b); }

the expressions

	*pickone() += 1;

and

	*pickone() = *pickone() + 1;

mean very different things.  But this is irrelevant.

The key is that the C language has op= operators, so you can expect
anyone reading C code to be familiar with them.  Since they more
concisely express the intended result, you should use them.  The
FORTRAN languages do not have op= operators, and you cannot expect
anyone reading FORTRAN code to be familiar with them.  While they more
concisely express the intended result, you should not use them lest you
confuse the reader.

Similarly, the FORTRAN language has the `**' operator.  It more
concisely expresses exponentiation than C's `pow()' function.  It
should be used ... in FORTRAN, and not in C.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris@mimsy.umd.edu	Path:	uunet!mimsy!chris