Managed C++/CLI

#include <iostream>
#include <cstring>
using namespace std;

class String
{
public:
    char *sir;
    String()
    {
        cout << "\n String() default called." << endl;
    }
    String(char *sir)
    {
        cout << "\n String() parameter called." << endl;
        if (this->sir != NULL)
            delete this->sir;
        this->sir = new char[strlen(sir)+1];
        strcpy(this->sir, sir);
    }
    String(String &box)
    {
        cout << "\n String() copy constructor called." << endl;
        this->sir = new char[strlen(box.sir)+1];
        strcpy(this->sir, box.sir);
    }
    void setString(char *sir)
    {
        cout << "\n setString() called." << endl;
        this->sir = sir;
    }
    char *getString()
    {
        return sir;
    }
    String operator=(String box)
    {
        cout << "\n String() Assigment operator called." << endl;
        String temp;
        strcpy(temp.sir, sir);
        strcat(temp.sir, box.sir);
        return temp;
    }
    String operator+ (String box)
    {
        String temp;
        strcpy (temp.sir, sir);
        strcat (temp.sir, box.sir);
        return temp;
    }
};

int main()
{
    String box1;
    box1.setString("Geeksforgeeks");
    cout << "\n Box1::sir: " << box1.getString() << endl;
    String box2;
    box2.setString("GeeksQuiz");
    cout << "\n Box2::sir: " << box2.getString() << endl;
    box1 = box2;
    cout << "\n Box1::sir: " << box1.getString() << endl;
    String box3 = box2;
    cout << "\n Box3::sir: " << box3.getString() << endl;
    String box4;
    box4 = box1 + box2;
    cout << "\n Box4::sir: " << box4.getString() << endl;
    return 0;
}