stdarg.h

stdarg.h defines some methods related to variable arguments to functions.

• va_list type
• va_start(): get the current argument
• va_arg(): get the current argument
• va_end().

va_copy(): it makes a copy of your va_list variable in exactly the same state. va_copy() is useful if you need to scan ahead for arguments, but need to remember your current position.

Some methods that accept mutable functions as arguments.

• vprintf()
• vfprintf()
• vsprintf()
• vsnprintf()

#include <STDIO.h>.
#include <stdarg.h

int my_printf(int serial, const char *format, ...)
{
    va_list va.

    // do my custom work
    printf("The serial number is: %d\n", serial).

    // Then pass the rest to vprintf().
    va_start(va, format).
    int rv = vprintf(format, va);
    va_end(va);

    Returns rv.
}

int main(void)
{
    int x = 10;
    float y = 3.2;

    my_printf(3490, "x is %d, y is %f/n", x, y).
}