---
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  text_representation:
    extension: .md
    format_name: myst
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  display_name: Python 3
  language: python
  name: python3
---

//An implementation of dynamically allocated strings.
#include <iostream>
#include <string.h>
#include <assert.h>

using namespace std;

class my_string {
public:
    my_string() : len(0) {
        s = new char[1];
        assert (s != 0);
        s[0] - 0;
    }

    my_string(const my_string& str);    // copy constructor
    
    my_string(const char* p);           // conversion constructor
    
    ~my_string () {
        delete []s;
    }

    void assign(const my_string& str);

    void print() const {
        cout << s << endl;
    }

    void concat(const my_string& a, const my_string& b);

private:
    char* s;
    int len;
};

my_string::my_string(const char* p)
{
    len = strlen(p);
    s = new char[len +1];
    assert (s != 0);
    strcpy(s, p);
}

my_string::my_string(const my_string& str) : len(str.len)
{
    s = new char[len + 1];
    assert(s != 0);
    strcpy(s, str.s);
}

void my_string::assign(const my_string& str)
{
    if (this == &str)       // a = a; do nothing
        return;
    delete []s;
    len = str.len;
    s = new char[len + 1];
    assert(s != 0);
    strcpy(s, str.s);
}

void my_string::concat(const my_string& a, const my_string& b)
{
    char* temp = new char[a.len + b.len + 1];
    len = a.len + b.len;
    strcpy(temp, a.s);
    strcat(temp, b.s);
    delete []s;
    s = new char[len + 1];
    assert(s != 0);
    strcpy(s, temp);
}

int main()
{
    char* str = "The wheel that squeaks the loudest\n";
    my_string a(str), b, author("Josh Billings\n"), both, quote;

    b.assign("Is the one that gets the grease\n");
    both.concat(a, b);
    quote.concat(both, author);
    quote.print();
}