copy-cons.cpp

#include <iostream>
#include <string.h>

int line;

class String {
    public:

    char* m_buffer;
    size_t m_size;

    // copy cons
    String(const char* string) {
        m_size = strlen(string);
        m_buffer = new char[m_size+1];
        strcpy(m_buffer, string);
        std::cout << line << " constructor from char* " << m_buffer << " " << intptr_t(m_buffer) << "\n";
    }
    String(const String& other) {
        m_size = other.m_size;
        m_buffer = new char[m_size+1];
        strcpy(m_buffer, other.m_buffer);
        std::cout << line << " constructor from other " << m_buffer << " " << intptr_t(m_buffer) << "\n";
    }
    String(String&& other) {
        m_size = other.m_size;
        m_buffer = other.m_buffer; // copy just the pointer!
        other.m_size = 0;
        other.m_buffer = nullptr;
        std::cout << line << " move from other " << m_buffer << " " << intptr_t(m_buffer) << "\n";
    }
    String() {}
    ~String() {
        std::cout << line << " delete " << m_buffer << " " << intptr_t(m_buffer) << "\n";
        delete[] m_buffer;
    }
};

void f(const String& s) {
    String copy{s};
    std::cout << line << " f(" << copy.m_buffer << ")\n";
}

int main()
{
    line = __LINE__; String s = "hello";
    line = __LINE__; String a{"hi"};
    line = __LINE__; String b = s;
    line = __LINE__; String c{s};
    line = __LINE__; f(String("bye"));
    line = __LINE__; f(std::move(String("bye")));
}