Re: C decimal question:

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Post #72,376

by deSitter

1/3/03 9:26:50 PM

Re: C decimal question:

Try

1) Append an L to the integer

2) typecast the integer as whatever the denominator is

This is an implicit conversion issue I think. I would automatically typecast the integer. In pure C, typecasting is not obscene, but helpful.

-drl

Post #72,884

by admin

1/6/03 10:15:39 AM

Makes no difference.

The original code is as follows, what I gave is merely a distilled test case:

\n\tinline double To_double() const\n\t{\n\t\tsize_t len = 0;\n\t\tconst char *s = ptr(&len);\n\t\tchar sz[ISIZE+FSIZE+1];\n\t\tmemcpy(sz, s, len);\n\t\tsz[len] = 0;\n\t\tdouble d = atof(sz);\n\t\treturn d / pow(10.0, FSIZE);\n\t}\n

sz is being set up with "123456". FSIZE is 3. I was comparing 123.456 with the results of To_double. Again, this works fine on gcc 2.95.mumble and VC++6.

Regards,

-scott anderson

"Welcome to Rivendell, Mr. Anderson..."

C decimal question: - (admin) - (53) - Jan. 3, 2003, 05:53:14 PM EST

Equality on Real/Double is always a crapshoot - (tablizer) - Jan. 3, 2003, 06:04:04 PM EST

Don't know... - (Simon_Jester) - Jan. 3, 2003, 06:04:45 PM EST

Re: C decimal question: - (deSitter) - (1) - Jan. 3, 2003, 09:26:50 PM EST

Makes no difference. - (admin) - Jan. 6, 2003, 10:15:39 AM EST

The boolean compare operators - (ChrisR) - (36) - Jan. 4, 2003, 02:12:52 AM EST

I've done the subtract - (admin) - (35) - Jan. 4, 2003, 08:50:00 AM EST

Assembly dump? - (ChrisR) - (22) - Jan. 4, 2003, 12:57:27 PM EST

I did my dump with GDB - (Arkadiy) - Jan. 5, 2003, 02:11:21 PM EST

What I get: - (admin) - (20) - Jan. 6, 2003, 10:34:38 AM EST

Speculating... - (ChrisR) - (19) - Jan. 6, 2003, 10:49:00 AM EST

gcc 2.95.4 results - (admin) - (18) - Jan. 6, 2003, 11:06:04 AM EST

Re: gcc 2.95.4 results - (deSitter) - (1) - Jan. 6, 2003, 11:35:48 AM EST

EBP is base of stack frame - (Arkadiy) - Jan. 6, 2003, 01:18:01 PM EST

I86 Assembly is not my specialty... - (ChrisR) - Jan. 6, 2003, 12:30:53 PM EST

ASM Comments - (ChrisR) - (13) - Jan. 6, 2003, 02:12:59 PM EST

Errrr... - (admin) - (12) - Jan. 6, 2003, 03:08:52 PM EST

Getting ASM from VC6 - (deSitter) - (11) - Jan. 6, 2003, 04:06:35 PM EST

Results - (deSitter) - (10) - Jan. 6, 2003, 04:25:49 PM EST

Request... - (ChrisR) - (9) - Jan. 6, 2003, 04:34:54 PM EST

Re: Request... - (deSitter) - (8) - Jan. 6, 2003, 04:36:04 PM EST

Trimming it down... - (ChrisR) - (7) - Jan. 6, 2003, 04:57:34 PM EST

Re: Trimming it down... - (deSitter) - (6) - Jan. 6, 2003, 04:57:55 PM EST

Scratches head... - (ChrisR) - (5) - Jan. 6, 2003, 06:07:55 PM EST

Re: Scratches head... - (deSitter) - (4) - Jan. 6, 2003, 08:51:33 PM EST

Thanks... - (ChrisR) - (3) - Jan. 6, 2003, 09:27:16 PM EST

BTW - (deSitter) - (2) - Jan. 6, 2003, 09:29:58 PM EST

Hmmmm - (ChrisR) - (1) - Jan. 6, 2003, 10:10:48 PM EST

puts("42"); -NT - (deSitter) - Jan. 6, 2003, 10:21:20 PM EST

gcc 2.95.26 - (ChrisR) - Jan. 6, 2003, 06:13:49 PM EST

Did you try it with optimizations off? -NT - (deSitter) - (7) - Jan. 4, 2003, 01:12:28 PM EST

A really good optimizing compiler... - (ChrisR) - (6) - Jan. 4, 2003, 01:21:38 PM EST

Yes.. - (deSitter) - Jan. 4, 2003, 01:35:10 PM EST

Compiler has no way to predict how pow() is implemented - (Arkadiy) - (4) - Jan. 5, 2003, 02:13:15 PM EST

IEEE - (deSitter) - (2) - Jan. 5, 2003, 02:23:03 PM EST

pow() is library, not hardware - (Arkadiy) - (1) - Jan. 5, 2003, 07:14:41 PM EST

True - (deSitter) - Jan. 5, 2003, 07:38:57 PM EST

Re: Compiler has no way to predict how pow() is implemented - (deSitter) - Jan. 5, 2003, 08:57:17 PM EST

An option of interest? - (ChrisR) - (3) - Jan. 4, 2003, 01:13:29 PM EST

I'll look into that. Datum: gcc 3.2.1 on glibc 2.3.1 -NT - (admin) - Jan. 4, 2003, 05:56:33 PM EST

Doesn't seem to make any difference. - (admin) - (1) - Jan. 6, 2003, 10:12:59 AM EST

Re: Doesn't seem to make any difference. - (deSitter) - Jan. 6, 2003, 11:36:57 AM EST

Not a direct answer, but still on-topic. - (static) - Jan. 4, 2003, 04:52:08 AM EST

RESOLUTION: - (admin) - (10) - Jan. 6, 2003, 07:34:23 PM EST

A caveat from Borland: - (a6l6e6x) - (6) - Jan. 6, 2003, 08:14:49 PM EST

This was slightly different. - (admin) - (5) - Jan. 6, 2003, 08:17:18 PM EST

Re: This was slightly different. - (deSitter) - Jan. 6, 2003, 09:11:32 PM EST

Oh - to discover a real compiler problem - (deSitter) - (1) - Jan. 6, 2003, 09:36:04 PM EST

This is not considered a compiler problem by the GCC folks. - (admin) - Jan. 6, 2003, 10:18:20 PM EST

Scott, that's a bug worthy of catching - (Simon_Jester) - (1) - Jan. 6, 2003, 10:34:21 PM EST

Fun to track down, at least. - (admin) - Jan. 6, 2003, 10:37:27 PM EST

Re: RESOLUTION: - (deSitter) - (2) - Jan. 6, 2003, 09:03:59 PM EST

Historically speaking... - (ChrisR) - (1) - Jan. 6, 2003, 09:53:48 PM EST

Re: Historically speaking... - (deSitter) - Jan. 6, 2003, 10:04:39 PM EST

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