Overloading assignment operator with Classes and Vectors

Question

I have a class defined:

#ifndef _STRINGCLASS_H
#define _STRINGCLASS_H
using namespace std;

#include <iostream>
#include <vector>

class String {
protected:
    int length;
    vector<string> buf;

public:
    String();
    String(const char* input);
    String(char input);
    String(int input);
    String(const String& input);
    String(char input, int input2);

    String& operator=(const String& input);


};

#endif

and am trying to overload the assignment operator by such:

String& operator=(const String& input) {

    buf = input.buf;
    length = input.length;

    return *this;
}

and I get the error code that buf is protected and length is protected. I'm not sure what I am missing. How can I properly overload the assignment operator with vectors and ints?

The implicitly-generated assignment operator does the same thing, so if you don't have anything else in the function besides what you have shown here then it'd be better to not define it yourself (or define as `default` in C++11) — M.M, Aug 05 '14 at 05:21

score 2 · Answer 1 · answered Aug 05 '14 at 05:34

You do not need to provide any special member functions for your class, because the compiler synthesized ones will do the right thing in this case. The best option is to remove the assignment operator and copy constructor from your class definition.

class String 
{
protected:
    int length;
    vector<string> buf;

public:
    String();
    String(const char* input);
    String(char input);
    String(int input);
    String(char input, int input2);
};

score 1 · Accepted Answer · edited May 23 '17 at 11:49

You need to define the implementation as part of the class. You are missing the class specifier:

//      vvvvvvvv
String& String::operator=(const String& input) {

    buf = input.buf;
    length = input.length;

    return *this;
}

As written, you are defining a free operator overload (not bound to a class), and it's actually invalid to declare a free assignment operator overload anyway.

From the perspective of a free operator overload that isn't a member of String, buf and length are indeed inaccessible because they are private.

Overloading assignment operator with Classes and Vectors

2 Answers2