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soonc
Joined: 03 Dec 2013
Posts: 215
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| Variable name length |
 Posted: Thu Sep 15, 2016 11:55 am |
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CCS PCD C Compiler, Version 5.062, xxxxx
Is there a limit on the length of a variable name in source code ?
Example:
| Code: |
// as a global int16 variable
int16 g_n16ThisIsALongVariableNameUsedForTestingOnly = 0;
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My reason for asking is:
I have a situation where a long variable is not working.
| Code: | g_n16AnotherVar = 345;
g_n16ThisIsALongVariableNameUsedForTestingOnly = (g_n16AnotherVar * 2);
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g_n16ThisIsALongVariableNameUsedForTestingOnly value is Zero.
If I reduce the character length it works.
| Code: | g_n16AnotherVar = 345;
g_n16LongVariableName = (g_n16AnotherVar * 2); |
g_n16LongVariableName display as expected 690.
The lst file has the same instructions for both statements ! |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Thu Sep 15, 2016 4:48 pm |
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this is NOT hard to test.
Last edited by asmboy on Thu Sep 15, 2016 4:58 pm; edited 1 time in total |
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soonc
Joined: 03 Dec 2013
Posts: 215
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| Posted: Thu Sep 15, 2016 4:53 pm |
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| asmboy wrote: | this is NOT hard to test.
and the LST file is your friend. |
Yes as I said the LST file produces the same code, but the variable remains at zero !
When I changed the variable name to something shorter it works....
I'd like to know if there is a limit to the length of a variable name. |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Thu Sep 15, 2016 4:54 pm |
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Limit name to 31 chars or less.
Ditto function names and labels in general.
Stay under 32 and be happy.
and BTW #define is limited to 254 chars.
Last edited by asmboy on Thu Sep 15, 2016 5:05 pm; edited 2 times in total |
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temtronic
Joined: 01 Jul 2010
Posts: 9226
Location: Greensville,Ontario
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| Posted: Thu Sep 15, 2016 4:55 pm |
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Interesting, as I've never seen a 'keywords..do not use' list in the manual..
Those lists were in every BASIC book I used, long, long ago....
I can't type worth a damn, so I use short words, typically 3 letter groups (from ASM and COBOL days) that mean something when I program, then months latter...'What does this mean ??', sigh, old age is fun !!
Jay |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Sep 15, 2016 7:30 pm |
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| Quote: | I have a situation where a long variable is not working.
If I reduce the character length it works.
g_n16LongVariableName display as expected 690. |
I don't have the PCD compiler, so I compiled it in PCH vs. 5.062
and it worked. I got the following output in MPLAB vs. 8.92 simulator
in the SIM UART1 output window:
That's correct.
Test program:
| Code: | #include <18F4620.h>
#fuses INTRC_IO,NOWDT,PUT,BROWNOUT,NOLVP
#use delay(clock=4M)
#use rs232(baud=9600, UART1, ERRORS)
int16 g_n16AnotherVar = 345;
int16 g_n16ThisIsALongVariableNameUsedForTestingOnly = (g_n16AnotherVar * 2);
//======================================
void main(void)
{
printf("%lu %lu \r", g_n16AnotherVar, g_n16ThisIsALongVariableNameUsedForTestingOnly);
while(TRUE);
}
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I also tested it using "signed int16" and "%ld" and got the same thing. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Thu Sep 15, 2016 10:06 pm |
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The July 2016 PCD Reference Manual says on page 40:
| Quote: | Identifiers
ABCDE Up to 32 characters beginning with a non-numeric.
Valid characters are A-Z, 0-9 and _ (underscore). By
default not case sensitive Use #CASE to turn on. |
http://www.ccsinfo.com/downloads/PCDReferenceManual.pdf |
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soonc
Joined: 03 Dec 2013
Posts: 215
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| Thanks to all for the responses |
| Posted: Fri Sep 16, 2016 3:42 pm |
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Age... Same issue for me....
I could comment each var declaration but the comment does not follow the var through many pages of code, and that's why I adopted long variable name which is really the comment, and so for many years I'm relied on that.
I think Visual Studio allows longer names, which is where I got spoiled I guess ! |
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