Class as an argument and overloading

[Muffinthief]

Just a quick question:

1) Is it possible to pass the name of a class or struct as an argument ?
ex.
void function(class muffin)
{
muffin * y = new muffin;
}

you get the idea

2) How do I overload, or whatever, a class so that it can receive values from functions like scanf? How does the string class do this?

Thanks in advance!

[RRick]

You're close, but in C++ keywords like class and struct are usually used only in the declaration of the class or structure. You need to also pass a name of the object for muffin (i.e. y) in the parameter list.

I assume you want the value created inside the function to be used outside the function. In this case, a C style solution is:

void function( muffin **y)
{
    * y = new muffin;
}

A C++ style solution would be

void function( muffin *& y)
 {
    y = new muffin;
 }

Since y is not used inside the method, you can have the function simply return the value of the pointer. This way, you don't have to worry about passing a parameter.

muffin *  function( void)
 {
    muffin * y = new muffin;
    return y;
 }

[Muffinthief]

That's not quite what i meant...

I mean can you do something like this:

Class class1
{
   ...
};
 
void make_class(class chose)
{
   chose * x = new chose;
}
 
int main()
{
   make_class(class1);
   ...
}

and how about my second question?

[durand]

Just a quick question:

1) Is it possible to pass the name of a class or struct as an argument ?
ex.
void function(class muffin)
{
muffin * y = new muffin;
}

you get the idea

2) How do I overload, or whatever, a class so that it can receive values from functions like scanf? How does the string class do this?

Thanks in advance!

1)
Use templates instead.

// Base function
template <class T> // T = muffin
void function(T dummy) // dummy: any value of the required type
{
T * y = new T;
}

// specialization
template <> // T = muffin
void function<>(int dummy)
{
int * y = new int;
}

2) I did not understand very well but use function pointers to pass functions as arguments.

[RRick]

Durand is correct. Templates are the way to go here. You can't just declare the class in a parameter list because that defines a specific method with a specific value being passed.

As for your second question, I'm not sure what you want. Scanf "returns" an int. When you say you want to "receive values from scanf", all you're going to get it is an int saying how many things were parsed.

Scanf also takes accepts pointers to strings and other primitives and then sets them. Is this what you're talking about? In this case, you pass a pointer to the subroutine of what you want modified and the subroutine makes the changes.

Finally, scanf also takes what is called a variable length arguement list. This allows you to set the format and then add any number of variables.