Question

I have one clarification,

class Foo
{

}

main()   
{
   Foo obj; //1
   method(obj);
   method1(&obj);

   Foo* obj1;
   method2(&obj1);  //4

}

void method(Foo objfoo) //2
{

}

void method1(Foo* objfoo) //3
{

}

void method2(Foo* & objfoo){}

Q1. Will it allocates objects inside main stack frame ?

Q2. Will it create one more copy of Foo inside method stack frame ?

Q3. Will it point same object exists in obj present in main method ?

Q4. What this indicates ? need explanation ?

Answer 1

These are ordered by the Q1, Q2, etc., not the order they appear in the question.

1. Yes. (at least to the extent that there is a stack frame, or a stack).
2. Yes, at least in theory (in reality, the compiler may elide the copy though).
3. Yes, method1 receives a pointer to a pre-existing object.
4. It’s passing the address of obj1 to method2.

Aside: the call to method2 mentioned in Q4 won’t actually work. Since obj1 is defined as a pointer to a Foo, and method2 takes a reference to a pointer to a Foo, you would not need to (explicitly) take the address of the point to make the call. Doing so creates a pointer to a pointer, where method2 needs a reference to a pointer. Using method2(obj1); would be at least syntactically correct (open to question whether it will really work correctly though).