9. By using default arguments, we can write a function that
takes a variable number of arguments.

10. By default, 2 arguments are passed to main function..
One is the count that contains number of arguments + 1.
1 is for the program name.

Second argument is the array of arguments...with prgram name
at the first index i.e. [0] and the size of array is count-1.

WHERE IS THE ANSWER  MY FRIENDS?

The above reply is an vague idea for the concept idea some
details may be with an example will be an good input from
nay one of us

explained how we can utilize the operator ellipsis (…) to
pass variable number of arguments to a function. I have
utilised there the concept of pointers to access the
variable arguments. The standard C Library provides support
to access these arguments. Use for this support
All you need is to know the last argument before the
ellipsis operator(At least one argument is must to use
variable arguments), let’s call it larg

suppose

    fun(type var1,type var2,...)

is a function, then larg corresponds to var2

Now we need to declare the list using va_list
i.e.,

    va_list al

now initialize it using va_start

    va_start(al,larg);

Now to access each argument, we must know the expected type
of the argument

     type var_name = va_arg(al,type);

When we have accessed all the variable arguments, we need to
clean up

     va_end(al);

Using standard library, we can easily access the variable
arguments