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jgschmidt
Joined: 03 Dec 2008
Posts: 184
Location: Gresham, OR USA
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| Pointer problems - OOPS! User error. |
 Posted: Mon Jul 09, 2012 5:05 pm |
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Oops - this problem was caused by a conflict with an existing internal function: swap() is a CCS defined function
Hi,
I'm having some pointer problems. So I went to K&R to see what I might be doing wrong and wrote this minimalist pointer test code straight from the book, which generates the error. This compiles fine with PCC (Portable C Compiler) which I use for testing my hardware-independent C code.
| Code: | // 616PtrTest.c
//
// K&R 2ed. Pointer test from pg.95-6
//
// Target: PIC16F616 at 8 MHz internal
// Compiler: CCS PCWH 4.130
// Programmer: PICkit2
//------ Setup for 16F616
#include <16F616.h>
#device ANSI // this doesn't make any difference
#FUSES INTRC_IO //Internal RC Osc, no output
#FUSES NOWDT //No Watch Dog Timer
#FUSES NOPUT //No Power Up Timer
#FUSES NOMCLR //Engages weak pullup
#FUSES NOBROWNOUT //No brownout reset
#use delay(internal=8M)
#use rs232( BAUD=38400, XMIT=PIN_A4, INVERT )
void swap( int *a, int *b )
{
int temp;
printf("fn1: %d %d\r\n",*a, *b);
temp = *a;
*a = *b;
*b = temp;
printf("fn2: %d %d\r\n",*a, *b);
}
main()
{
int i=3, j=5;
printf("before: %d %d \r\n",i,j);
swap( &i, &j );
printf("after: %d %d \r\n",i,j);
} |
Right now this doesn't even compile. I get the dreaded "Error 49: Expecting LVALUE..." on the function call. The &j is highlighted.
What am I doing wrong?
Thanks in advance for any help.
_________________
Jürgen
www.jgscraft.com |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Tue Jul 10, 2012 1:42 am |
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Your problem is simple. Nothing fundamental with the code, except one thing. Using the name 'swap' for the function. In CCS, 'swap' is a reserved keyword, for the function to swap nibbles in a byte. Hence it goes wrong.....
Call the function something like 'my_swap', and it'll all start working.
Best Wishes |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19504
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| Posted: Tue Jul 10, 2012 1:43 am |
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I see you have spotted this. 
Best Wishes |
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