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Re: va_arg() question

Artie Gold
Posts: n/a
      08-07-2003 Removed) wrote:
> Hello all,
> I have a quick question regarding the use of va_arg() with multiple
> parameter definitions. If the parameters are of different types, how
> do I know what type it is when using va_arg() ????
> For example, if I was to write a function similar to the good old
> printf() which takes multiple parameters of different types (eg. int,
> char*, etc) how do I know whether the parameter I'm processing is an
> int or a char* ???

The same way printf() does.

When you supply a format to printf(), it parses it to see what type of
variable(s) to expect.

For example, if you write

int i = 3;
char * name_of_i = "i";
printf("the value of %s is %d", name_of_i, i);

the first directive it sees is `%s', so it takes the second argument to
be a pointer to char. Then it sees `%d' and takes the third argument to
be an int.

While you can use any method you want, any variadic function needs some
way of knowing what type(s) of variable(s) to expect.


Artie Gold -- Austin, Texas

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