Rahul wrote:
I have the following code,
[code similar to:]
#include <iostream>
struct A {
A() { std::cout << "in A\n"; }
~A() { std::cout << "in ~A\n"; }
A operator++(int) {
std::cout << "in operator function\n";
return A();
}
};
int main() {
A obj;
std::cout << "1\n";
obj++;
std::cout << "2\n";
return 0;
}
and the output i get is,
in A
1
in A
in operator function
in ~A // Destructor for local
object in operator function
in ~A // Destructor is invoked for
which object???
2
in ~A
I think you may have copied either the code or the output
incorrectly. Your output indicates two invocations of
operator++(int), but the code shows only one.
What you should be seeing is:
in A
1
in operator function
in A
in ~A
2
in ~A
The inner constructor/destructor pair is for the temporary object
returned by the post-increment function.
second, is it possible to have the operator++(int) [postfix
operator+ +] to return a reference? As per my program it isn't
possible as returning reference of a local variable doesn't make
any sense...
It's possible, but it rarely makes sense. In general, it is
better to define the pre-increment operator first, and return the
current object by reference:
A& operator++() {
// ... increment this object ...
return *this;
}
If you need post-increment, you can them implement it like this:
A operator++(int) {
A const old_value = *this;
++*this;
return old_value;
}