c++ - Return using this pointer vs return by value -

what difference between returning pointer , return value.

i try explain case example..

i have following code

#include <iostream> using namespace std;  class count {     private:          int count;            public:          //constructor         count():count(0) { cout << "constructor called" << endl; }          count(count& c):count(c.count)         {               cout << "copy constructor called" << endl;          }          //destructor         ~count() { cout << "destructor called" << endl; }          count  operator ++ () {             count++;             count temp;             temp.count = count;             return temp;             //return *this;          }          //display value.          void display() {              cout << "the value of count " << count << endl;          }  };  int main() { count c; count d; c.display(); d.display(); d=++c; c.display(); d.display(); return 0; } 

i have following function in class

count  operator ++ () {         count++;         count temp;         temp.count = count;         return temp; } 

when use above function, see normal constructor called when returning value.

but change function below

count  operator ++ () {         count++;         return *this; } 

the above function calls copy constructor when returning pointer.

can me understand difference.

your return *this not "return pointer". this pointer, *this not pointer, object of count type. return *this returns current value of *this value, i.e. returns copy of count object.

the return temp version same thing, unexplainable reason first stores current state of *this in local variable temp , returns temp. don't know point of doing is.

both variants same thing. both return value in case. both versions call copy constructor (at least conceptually, call can optimized out).