Forwarding Variable Argument Lists

[joecook]

I thought I could have a wrapper over a function that takes a variable
argument list, but it doesn't work. (it compiles, but does not produce
expected results) Anything pop out?

#include <iostream>
#include <cstdarg>

using namespace std;

void foo(const char* fmt, ...)
{
va_list ap;
va_start(ap,fmt);
printf(fmt,ap);
va_end(ap);

}

int main()
{
foo("This is a number: %d",44);

}

Thanks,
Joe C

 

[Pascal J. Bourguignon]

I thought I could have a wrapper over a function that takes a variable
argument list, but it doesn't work. (it compiles, but does not produce
expected results) Anything pop out?

#include <iostream>
#include <cstdarg>

using namespace std;

void foo(const char* fmt, ...)
{
va_list ap;
va_start(ap,fmt);
printf(fmt,ap);
va_end(ap);

}

Indeed this is not possible like this.

If you want to call a random function, you will have to use a library
such as ffcall, which will push the parameters on the stack for you.


But happily, if what you want is only the printf functionality, you
can call instead vprintf.