jdc@naucse.UUCP (John Campbell) (02/09/88)
Do all bugs bite? This short program ran under unix on a 3b1 (and Ultrix).
On VMS but it failed because I forgot =- is an "old-fashioned" initialization
(I was in a hurry :-). In hindsight, my 3b1, did the same, but "x" was 0.
On VMS x is 0 in the debugger--otherwise it's garbage. Neither VMS or the
3b1 said a thing about this section of code! My third try, on Ultrix, warned:
line 6: warning: ambiguous assignment: assignment op taken
line 6: warning: old fashioned assignment operator
Lint (which I don't have on VMS) added:
line 6: warning: x be used before set.
So, two out of three compilers agree--give the user a quiet history lesson!
(Is =- in dpAns 'C'?) (Are warning messages so awful?)
#include <math.h>
#define PI 3.14159265
main ()
{
float x;
for (x=-3*PI; x < 3*PI; x += PI/8.0) /* Change to x = -3*PI */
printf ("%f %f\n", x, sin(x)/x);
}
--
John Campbell ...!arizona!naucse!jdc
unix? Sure send me a dozen, all different colors.ftw@datacube.UUCP (02/12/88)
jdc@naucse.UUCP writes: > So, two out of three compilers agree--give the user a quiet history lesson! > (Is =- in dpAns 'C'?) (Are warning messages so awful?) [code deleted] I don't beleive that =op is in dpANS. Some compilers *wouldn't* issue a warning, and quietly give you =op instead of = (unary)op. Whitesmith's used to do this. > John Campbell ...!arizona!naucse!jdc Farrell T. Woods Datacube Inc. Systems / Software Group 4 Dearborn Rd. Peabody, Ma 01960 VOICE: 617-535-6644; FAX: (617) 535-5643; TWX: (710) 347-0125 INTERNET: ftw@datacube.COM UUCP: {rutgers, ihnp4, mirror}!datacube!ftw "OS/2 -- Half an operating system"
henry@utzoo.uucp (Henry Spencer) (02/22/88)
> I don't beleive that =op is in dpANS...
Correct; it isn't. The Rationale does note this as a "quiet change", i.e.
one that can silently break existing code, but observes that even K&R said
that =op was obsolete. I expect that most sensible compilers will continue
to complain about anything that looks like =op for quite a while yet.
--
Those who do not understand Unix are | Henry Spencer @ U of Toronto Zoology
condemned to reinvent it, poorly. | {allegra,ihnp4,decvax,utai}!utzoo!henry