What does “Class* &cls” mean in C++'s function definition?

Question

I know Class *cls is a pointer, and Class &cls takes the address, but what is

void fucction1( Class *&cls)

If I have Class c

Answer 1

As said, a reference to a pointer to Class.

• you pass a Class * to the function
• the function may change the pointer to a different one

This is a rather uncommon interface, you need more details to know what pointers are expected, and what you have to do with them.

Two examples:

Iteration

bool GetNext(Classs *& class)
{
   if (class == 0)  
   {
     class = someList.GetFirstObject();
     return true;
   }

   class = somePool.GetObjectAbove(class); // get next
   return class != 0;       
}

// Use for oterating through items:
Class * value = 0;
while (GetNext(value))
   Handle(value);

Something completely different

void function (Class *& obj)
{
    if (IsFullMoon())
    {
      delete obj;
      obj = new Class(GetMoonPos());
    }
}

In that case, the pointer you pass must be new-allocated, and the pointer you receive you need to pass either to function again, or be delete'd by you.