Functions with different value of default arguments

Question

How to parse function arguments, when all have default values and only some of them are used? Example: I have a function with several arguments with default values

void fun(string a="", int b=0, string c="", int d=0)
{
 //parse used arguments somehow
}

I want to use it with different value of arguments, for example:

fun("foo", 10);
fun(10, 10);

How can I determine which arguments were used? Maximum value of arguments is known and order will be always the same. I do not want to run function like:

fun("", 3, "", 10);

And I cannot use variadic functions.

Any ideas?

"How can I determine which arguments were used?" You can't. I'm also fairly certain fun(10, 10); will either not compile as 10 is not a string, or will not do what you expect (it'll probably assume 10 is a pointer to a char*) — Borgleader
– Borgleader, Commented Nov 20, 2014 at 14:49
@Borgleader, Nah, it won't compile. std::string deliberately made sure of that. — Qaz
– Qaz, Commented Nov 20, 2014 at 14:50
@chris It will if you call with 0 instead like so foo(0, 10); which is a really nasty bug source in this case. — Borgleader
– Borgleader, Commented Nov 20, 2014 at 14:55

timrau · Accepted Answer · 2014-11-20 14:49:41Z

3

Overload the function.

void fun(int b, int d) { fun("", b, "", d); }

Then fun(3, 10) becomes equivalent to fun("", 3, "", 10).

answered Nov 20, 2014 at 14:49

timrau

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