accelerated c++ excercise 12-3

[axcelenator]

The question says:

Define the relational operators for Str. In doing so, you will want to know that
the <cstring> header defines a function called strcmp, which compares two character
pointers. The function returns a negative integer if the null-terminated character array
denoted by the first pointer is less than the second, zero if the two strings are equal, or
a positive value if the first string is greater than the second.

I try to build some member function for < but i got stuck:

 

class MyString
{
public:

    //default constructor, create an empty string
    MyString() 
    {

    };

    //create a string containing n copies of c
    MyString(size_t n, char c) :data(new char[n]), data_length(n)
    {
        for (size_t i = 0; i < n; i++)
        {
            data[i] = c;
        }
    };

    //create a string from a null-terminated array
    MyString(const char *cp):data(new char[std::strlen(cp)]), data_length(std::strlen(cp))
    {
        //std::copy(cp, cp + std::strlen(cp), data);
        std::copy(cp, cp + std::strlen(cp), stdext::checked_array_iterator<char*>(data, data_length));
    }

    //destructor
    ~MyString()
    {
        //free the array
        delete[] data;  
    };


    //relational operator <
     bool operator<(const char* rhs)
	{
		return strcmp(this->data, rhs);
	}

private:
    size_t data_length;
    char* data;
};

Inside the main how do I use that?
I tried to code it like that but compiler complains:

int main()
{
	

	MyString mystr1(3,'a');
	MyString mystr2("alon");
	if ((mystr1<mystr2))
		std::cout << "equal";
    return 0;
}

Can you give some example how should I implement such a code and how to check it inside the main?

[Enoizat]

I don’t have Visual Studio, so I needed to exclude the Ms extensions.

MyString.h:

// Define the relational operators for Str. In doing so, you will want to know 
// that the <cstring> header defines a function called strcmp, which compares 
// two character pointers. The function returns a negative integer if the 
// null-terminated character array denoted by the first pointer is less than 
// the second, zero if the two strings are equal, or a positive value if the 
// first string is greater than the second.
#ifndef MYSTRING_H
#define MYSTRING_H

class MyString
{
public:
    //default constructor, create an empty string
    MyString();

    //create a string containing n copies of c
    MyString(size_t n, char c);

    //create a string from a null-terminated array
    MyString(const char *cp);

    //destructor
    ~MyString();

    //relational operator <
    bool operator<(const MyString& rhs);

private:
    size_t data_length;
    char* data;
};

#endif // MYSTRING_H 

MyString.cpp:

#include <algorithm>
#include <cstring>
#include "MyString.h"

//default constructor, create an empty string
MyString::MyString() : data_length{}, data{nullptr} {}

//create a string containing n copies of c
MyString::MyString(size_t n, char c) : data_length(n), data(new char[n])
{
    for (size_t i = 0; i < n; i++) { data[i] = c; }
}

//create a string from a null-terminated array
MyString::MyString(const char *cp)
    : data_length(std::strlen(cp)), data(new char[std::strlen(cp)])
{
    std::copy(cp, cp + data_length, data);
}

//destructor
MyString::~MyString()
{
    delete[] data; //free the array
}

//relational operator <
bool MyString::operator<(const MyString& rhs)
{
    if(strcmp(data, rhs.data) < 0) { return true; }
    else                           { return false; }
}

main.cpp:

#include <iostream>
#include "MyString.h"

int main()
{
    MyString mystr1(3, 'a');
    MyString mystr2("alon");
    if(mystr1 < mystr2) { std::cout << "mystr1 is less than mystr2\n"; }
    return 0;
}