Allowing indefinite function arguments using stdarg.h

Introduction

Introduction

The following declares the new type va_list at the start.

Then between va_start and va_end we can access arguments using va_args repeatedly, while giving it the type to take out.

void my_function(int count, ...) {

    va_list args;
    int i;
    va_start(args, count);
    for (i = 0; i < count; i++) {
        int num = va_arg(args, int);
    }
    va_end(args);
}

When we traverse va_arg we can’t go back. Another approach is to use va_copy to take a copy of the args before going through them.

void my_function(int count, ...) {

    va_list args;
    int i;
    va_start(args, count);
    va_copy(args_copy, args);
    for (i = 0; i < count; i++) {
        int num = va_arg(args, int);
    }
    for (i = 0; i < count; i++) {
        int num = va_arg(args_copy, int);
    }
    va_end(args);
    va_end(args_copy);
}