C and embedded

Tue, 03 Nov 2009 00:02:41 -0800

#include <stdio.h>
#include <conio.h>
#define RW 0
#define write() RW|=1
int main()
{
printf("Before \n%d",RW);
write();
printf("After calling WRITE \n%d",RW);
getch();
return 0;
}

Hi all

Iam new to embedded programming with C
In the above program Iam trying to modify a macro with #define
Its not working
Please tell me where I went wrong

Re: C and embedded

Thu, 05 Nov 2009 06:24:46 -0800

hi,
Because RW is a macro define, its value can't be changed. In your program, define write() with RW |= 1, and when this program is compiled, write() will be replaced with 0 |= 1, it is impossible.
if you want to change the value of RW, you can use this:
#include <stdio.h>

static unsigned int RW = 0;

__inline write()
{
RW |= 1;
}

int main()
{
printf("Before \n %d", RW);
write();
printf("After calling WRITE \n %d", RW);
getchar();

return 0;
}

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