Difference between exit(0) and return 0 in C++:-

When exit(0) is used to exit from program, destructors for locally scoped non-static objects are not called. But destructors are called if return 0 is used.

Program 1 – – uses exit(0) to exit

class Test {
public:
  Test() {
    cout<<"Inside Test's Constructor\n";
  }

  ~Test(){
    cout<<"Inside Test's Destructor";
  }
};

int main() {
  Test t1;
  exit(0);    //using exit(0) to exit from main
}

Output:-

Inside Test’s Constructor

Program 2 – uses return 0 to exit

class Test {
public:
  Test() {
    cout<<"Inside Test's Constructor\n";
  }

  ~Test(){
    cout<<"Inside Test's Destructor";
  }
};

int main() {
  Test t1;
  return 0;   //using return 0 to exit from main
}

Output:

Inside Test’s Constructor
Inside Test’s Destructor

Calling destructors is sometimes important, for example, if destructor has code to release resources like closing files,deleting dynamically allocated memory etc.

if class object is static:- Note that static objects will be cleaned up even if we call exit(). Reason:-static objects are allocated storage in static storage area. static object is destroyed at the termination of program.

For example, see following program.

class Test {
public:
  Test() {
    cout<<"Inside Test's Constructor\n";
  }

  ~Test(){
    cout<<"Inside Test's Destructor";
  }
};

int main() {
  static Test t1;  ///* Note that t1 is static*/

  exit(0);
}

Output:

Inside Test’s Constructor
Inside Test’s Destructor