Posted on May 17, 2011 at 11:35 I have been having problems using stdarg.h. I made a function:
LCD_printf(const char *c_ptr, ...)
{
va_list ap;
unsigned char c;
unsigned char c;
va_start(ap, c_ptr);
while (*c_ptr != '\0')
{
c = *c_ptr;
c_ptr++;
if (c == '%') {
d = *c_ptr;
c_ptr++;
d &= 0x0F;
c = va_arg(ap, unsigned char);
LCD_WrDec(c,d);
}
else
LCD_WrByte(c);
}
va_end(ap);
}
I call the function with something like this:
LCD_printf(''Data values: %1 & %2'', value1, value2);
The function worked the first couple of times, but then I added some things to it, it broke and I can not get it back to working. I added an extra argument and it worked for awhile, but then broke again. The problem is that it was trashing the *c_ptr variable value unless I remove the ellipses (, ...). The only way I could get it to work is adding a dummy variable so it can trash it instead of the character pointer:
LCD_printf(const char *c_ptr, unsigned char x, ...) { // x is dummy va_start(a_ptr, x);
I have to then call it with something like:
LCD_printf(''Data values: %1 and %2'', 0, value1, value2);
Well, that worked for awhile, but then it started giving me the wrong
values for the variable arguments. I'm wondering if this has ever been tested.
Any know issues or ideas?
[ This message was edited by: Smiles on 06-10-2003 10:10 ]
