Operator overloading using deep copy in c++

Question

#include<iostream>
#include<cstring>
#include<conio.h>
using namespace std;
class String 
{
  char *value;
  int len;

  public:
  String()
  {
    len=0;
    value=0;
  } 
  ~String() {}

  String(char *s)
  {
    len=strlen(s);
    value=new char[len+1];
    strcpy(value,s);

  }
  String(String & s)
  {
    len=s.len;
    value=new char[len+1];
    strcpy(value,s.value);
  }


 friend String operator+(String obj1, String obj2)
  {
    String obj3;
    obj3.len=obj1.len+obj2.len;
    obj3.value=new char [obj3.len+1];

    strcpy(obj3.value,obj1.value);
    strcat(obj3.value,obj2.value);
    return obj3;
    }

   friend  String operator=(String obj1, String obj2)
    {

        String obj3;
        strcpy(obj3.value,obj1.value);
        strcat(obj3.value,obj2.value);
        return obj3;
    } 


  void display()

 { cout<<value<<endl; }

};


  int main()
 {

    String s1("Bodacious ");
    String s2("AllienBrain");
    String s3;
    s3=s1+s2;
    s3.display();

    getch(); 
 }

As I am already operated the operator + in my code but i also want to overload the operator= to conactenate both the strings but this code shows no error when i overload the + operator but it shows the correct output i.e. Bodacious AllienBrain.

But when i overload the operator= it throws error so anyone tell me whats wrong with me?

@ Yksisarvinen when i removed the friend tag it still throws errors — , Sep 27 '18 at 09:09
Possible duplicate of [What are the basic rules and idioms for operator overloading?](https://stackoverflow.com/questions/4421706/what-are-the-basic-rules-and-idioms-for-operator-overloading) — Richard Critten, Sep 27 '18 at 09:14
@A.kelly then you should be able to easily copy it from compiler console. — Rhathin, Sep 27 '18 at 09:16

score 0 · Answer 1 · answered Oct 01 '18 at 04:59

More appropriate version of overloaded = operator would be as below:

class String 
{
///...
String& operator=(const String& obj2)
  {
      if(this->value ){
        delete this->value;  // Free if existing
        this->value = NULL;
      }
      len = obj2.len;
      this->value = new char[len + 1];

      strcpy(this->value, obj2.value);
      return *this;
  }
///
};

Operator overloading using deep copy in c++

1 Answers1