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is this ANSI acceptable or not ??? [solved] -Octal confused

 
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asmboy



Joined: 20 Nov 2007
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is this ANSI acceptable or not ??? [solved] -Octal confused
PostPosted: Wed Jul 11, 2012 2:44 pm     Reply with quote

version 4.134

Quote:


CONST BYTE ok[4]={254,012,42,048}

Code:


will not compile , errors - with "numeric expected"

where as

CONST BYTE ok[4]={254,12,42,48}
Code:

DOES .... ?????

what kind of parser can't handle a leading zero ??



Last edited by asmboy on Wed Jul 11, 2012 6:21 pm; edited 1 time in total
gaugeguy



Joined: 05 Apr 2011
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PostPosted: Wed Jul 11, 2012 3:37 pm     Reply with quote

Wouldn't 012 be 12 Octal and not 12 decimal?
PCM programmer



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PostPosted: Wed Jul 11, 2012 4:22 pm     Reply with quote

Compile it in MSVC++ 6.0 (as a C file):
Code:

#include <stdio.h>

//======================================
void main(void)
{
const unsigned char ok[4]={254,012,42,048};

while(1);
}


It does not like illegal digits for numbers specified in Octal format (base 8):
Quote:

C:\Program Files\Microsoft Visual Studio\MyProjects\Test\Test.c(8) :
error C2041: illegal digit '8' for base '8'
Error executing cl.exe.
temtronic



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PostPosted: Wed Jul 11, 2012 5:49 pm     Reply with quote

yup typos can bite real bad.

O000O0O0

after a few hours ohs look like zeros.....

especially in some fonts !!!

It'd be nice to have zeros with a slash forced through them.
or at least the option to allow it for us , um, older guys with bifocals !!

jay
PCM programmer



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PostPosted: Wed Jul 11, 2012 5:54 pm     Reply with quote

It's not a typo. It's just a mistake. Example:
http://stackoverflow.com/questions/8459030/whats-wrong-with-array-declaration-invalid-digit-in-octal-constant
asmboy



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PostPosted: Wed Jul 11, 2012 6:22 pm     Reply with quote

thanks for the helpful explanation.

that number base had slipped from my pea brain
Very Happy Very Happy
temtronic



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PostPosted: Wed Jul 11, 2012 7:08 pm     Reply with quote

hmmm..not a typo...man my eyes are getting bad...still looks like a zero not a big oh to me, sigh, getting old sucks..

Last octal I did was in PDP-11 systems...back in '75...must admit it might not be 'common' anymore....

I do recall some systems allowing you to set the 'default' base for numbers entered in a program which is kinda handy.

I have used leading zeros in 3 digit decimal numbers to keep things visually aligned, making it easier to see 'funny' numbers.
gpsmikey



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PostPosted: Wed Jul 11, 2012 8:34 pm     Reply with quote

I still think in octal these days -- too many hours spent hand coding 8080/Z-80 assembler. Those processors were octal in opcode design - 176 was mov A,M while 167 was the reverse - mov M,A. Interestingly enough, the instruction for MOV M,M (166) was the HALT instruction. Used to have a little cardboard slide rule for figuring the opcodes for all the instructions ... come to think of it, I probably still have it down stairs :-)

mikey
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old engineering saying: 1+1 = 3 for sufficiently large values of 1 or small values of 3
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