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Gizz
Joined: 15 Jun 2004
Posts: 21
Location: Nottingham UK
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| Simple C char* question, old C hacks please help! |
 Posted: Wed Jun 16, 2004 7:01 am |
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Hi
Well, I'm up and running with the CCS compiler, and its nicer (so far) than the Hi-Tech one. But I seem to be forgetting my C (I'm a C# hack these days...).
I have the following:
void SendMessage(char* msg)
{
printf(msg);
putc(10);
putch(13);
}
Calling this like so:
SendMessage("A test message");
results in garbage being sent down the RS232.
Calling like so:
char temp[100];
strcpy(temp, "A test message");
SendMessage(temp);
works just fine.
Anyone know why the first instance fails?
Its an 877A using the PICDEM2 and ICD2
TIA! |
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Ttelmah
Guest
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| Re: Simple C char* question, old C hacks please help! |
| Posted: Wed Jun 16, 2004 8:07 am |
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| Gizz wrote: | Hi
Well, I'm up and running with the CCS compiler, and its nicer (so far) than the Hi-Tech one. But I seem to be forgetting my C (I'm a C# hack these days...).
I have the following:
void SendMessage(char* msg)
{
printf(msg);
putc(10);
putch(13);
}
Calling this like so:
SendMessage("A test message");
results in garbage being sent down the RS232.
Calling like so:
char temp[100];
strcpy(temp, "A test message");
SendMessage(temp);
works just fine.
Anyone know why the first instance fails?
Its an 877A using the PICDEM2 and ICD2
TIA! |
Probably one of the most common "FAQ's" for the CCS compiler. It does not support pointers to constant strings (this is in the manual)...
The second version, copies the constant string from ROM to RAM, and this can then be sent normally.
A search through the forum, looking for comments like 'pointers to ROM', will find some of the thousands of posts about this.
Best Wishes |
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SteveS
Joined: 27 Oct 2003
Posts: 126
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| Posted: Wed Jun 16, 2004 9:49 am |
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Oh, I see it's another one of your rude RTFM replies, Ttelmah!
(big time just kidding!!!! - I couldn't resist)
- SteveS |
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Gizz
Joined: 15 Jun 2004
Posts: 21
Location: Nottingham UK
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| Posted: Wed Jun 16, 2004 9:55 am |
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| OK, thanks, if I had a FM to FR I would! LOL! |
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Guest
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| Try this... |
| Posted: Wed Jun 16, 2004 10:39 am |
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As it's just a constant message, you could use
puts( " this is a message" );
Hans W |
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Guest
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| Posted: Wed Jun 16, 2004 8:26 pm |
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| Quote: |
void SendMessage(char* msg)
{
printf(msg);
putc(10);
putch(13);
}
Calling this like so:
SendMessage("A test message");
results in garbage being sent down the RS232.
|
Sounds like a job for the C preprocessor. A macro will behave like an inline function, and the compiler will generate the appropriate code for the context. |
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Ttelmah
Guest
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| Posted: Thu Jun 17, 2004 10:57 am |
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| Gizz wrote: | | OK, thanks, if I had a FM to FR I would! LOL! |
The 'FM', is on the web...
Best Wishes  |
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Haplo
Joined: 06 Sep 2003
Posts: 659
Location: Sydney, Australia
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| Posted: Thu Jun 17, 2004 5:46 pm |
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Here it is: FM  |
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