Question

EDIT: I don’t want to delete the post because I have learned a lot very quickly from it and it might do someone else good, but there is no need for anyone else to spend time answering or viewing this question. The problems were in my programming fundamentals, and that is something that just can’t be fixed in a quick response. To all who posted, thanks for the help, quite humbling!

Hey all, I’m working on building my own string class with very basic functionality. I am having difficulty understand what is going on with the basic class that I have define, and believe there is some sort of error dealing with the scope occurring. When I try to view the objects I created, all the fields are described as (obviously bad pointer). Also, if I make the data fields public or build an accessor method, the program crashes. For some reason the pointer for the object is 0xccccccccc which points to no where.
How can a I fix this? Any help/comments are much appreciated.

    //This is a custom string class, so far the only functions are 
    //constructing and appending

#include<iostream>
using namespace std;

class MyString1
{
public:
    MyString1()     
    {   

        //no arg constructor
        char *string;
        string = new char[0];
        string[0] ='\0';
        std::cout << string;
        size = 1;
    }
    //constructor receives pointer to character array
    MyString1(char* chars)
    {
        int index = 0;
        //Determine the length of the array
        while (chars[index] != NULL)
            index++;
        //Allocate dynamic memory on the heap
        char *string;
        string = new char[index+1];
        //Copy the contents of the array pointed by chars into string, the char array of the object
        for (int ii = 0; ii < index; ii++)
            string[ii] = chars[ii];
        string[index+1] = '\0';
        size = index+1;
    }
    MyString1 append(MyString1 s)
    { 
        //determine new size of the appended array and allocate memory
        int newsize = s.size + size;
        MyString1 MyString2;
        char *newstring;
        newstring = new char[newsize+1];

        int index = 0;
        //load the first string into the array
        for (int ii = 0; ii < size; ii++)
        {
            newstring[ii] = string[ii];
            index++;
        }

        for(int jj = 0; jj < s.size; jj++, ii++)
        {
            newstring[ii] = s.string[jj++];
            index++;
        }
        //null terminate
        newstring[newsize+1] = '\0';

        delete string;
        //generate the object for return
        MyString2.string=newstring;
        MyString2.size=newsize;

        return MyString2;
    }
private:
    char *string;
    int size;
};



int main()
{
    MyString1 string1;
    MyString1 string2("Hello There");
    MyString1 string3("Buddy");
    string2.append(string3);
    return 0;
}

EDIT:
Thank you everyone so far who has responded and dealing with my massive lack of understanding of this topic. I’ll begin to work with all of the answers, but thanks again for the good responses, sorry my question is vague, but there isn’t really a specific error, but more of a lack of understanding of arrays and classes.

Answer 1

Here’s just the mistakes from the first constructor.

    MyString1()     
    {   

//no arg constructor
        char *string;         //defines local variable that hides the member by that name
        string = new char[0]; //sort of meaningless
        string[0] ='\0';      //not enough room for that (out-of-bounds)
        std::cout << string;
        size = 1;             //I don't think you should count null as part of the string
    }

Similar mistakes elsewhere.

Also you should pass parameters in a more careful way.

MyString1(const char* source); //note const

MyString1 append(const MyString1& what); //note const and reference

If the latter is correct, also depends on what it is supposed to do. Based on std::string the expected result would be:

MyString1 a("Hello "), b("world");
a.append(b);
assert(a == "Hello world");