对象作为c ++中的默认值

Question

is there a way to have a default Object for parameters in C++ functions? I tried

void func(SomeClass param = new SomeClass(4));

and it worked. However how would I am I supposed to know wheter I have to free the allocated memory in the end? I would like to do the same without pointers, just an Object on the stack. is that possible?

Answer 1

void func(SomeClass param = new SomeClass(4));

This can't work because new returns a pointer

void func(SomeClass param = SomeClass(4));

should work and the object doesn't need to be freed.

Answer 2

You almost had it but you don't need the new keyword.

void func(SomeClass param = SomeClass(4));

This method has the advantage over using new in that it will be automatically deleted at the end of a call so no memory management is needed.

An alternative is to use shared pointers.

Answer 3

You could use overloading:

void func(const SomeClass&) const;
void func() const {
  SomeClass* param = new SomeClass(4);
  func(param);
  delete param;
}