Re: #define issues
Re: #define issues
- Subject: Re: #define issues
- From: Michael Rothwell <email@hidden>
- Date: Thu, 21 Apr 2005 22:37:54 -0400
More parentheses!
#define SET_ENTRY( (m),(r),(c),(e)) (m[(r)*4+(c)] = (e))
Michael Rothwell
email@hidden
On Apr 17, 2005, at 12:47 AM, Cameron Hayne wrote:
On 4/16/05 6:58 AM, "Aaron Boothello" <email@hidden> wrote:
typedef double matrix[16];
#define SET_ENTRY(m,r,c,e) (m[r*4+c] = e)
the 'macro' is called as follows (example):
SET_ENTRY(ret,1,1,4.5); //where ret is of type matrix
error generated is:incompatible types in assignment.
Well, there is nothing wrong in principle with this code.
I can compile and run the following program with no problem using gcc
3.3:
-------------------------
#include <stdio.h>
typedef double matrix[16];
#define SET_ENTRY(m,r,c,e) (m[r*4+c] = e)
matrix ret;
int main()
{
SET_ENTRY(ret,1,1,4.5);
printf("value set was %f\n", ret[5]);
return 0;
}
-------------------------
So probably your problem is due to something else sneaking in there and
redefining "matrix" or something.
In any case, the standard way to debug a problem with the preprocessor
is to
look at the C code after the preprocessor has done its thing.
E.g. via 'gcc -E'
It is usually obvious what is causing the trouble once you do that.
--
Cameron Hayne (email@hidden)
Hayne of Tintagel
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