Code Help

I need some coding help. It keeps crashing and is not printing
anything to the screen. I have no idea what to fix. Any help is
greatly appreciated.

Here is my driver:

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

 using namespace std;

 int main()
 {
  MyString fname;
  MyString lname("Smith");
  MyString mname(lname);
  MyString line, paper;
  MyString fullName;
  ifstream inData;

  fname = "Bob";

  fname = fname;

  cout << "first name: " << fname << endl;

     cout <<fname<<" "<<mname<<". "<<lname<<endl;

     inData.open("paper.txt");

     if(!inData)
     {
       cerr <<"Error: File NOT open\n";
       exit(0);
     }

     line.getline(inData);

     while(!inData.eof())
     {
       line += "\n";
       paper += line;
       line.getline(inData);
     }

     line += "\n";
     paper += line;

     cout <<"The paper has a length of "<<paper.length()<<".\n";
     cout << line;

     cout << "\n\n\n";

     cout << paper;

     cout << "\n\n\n";

     //Test the = operator
     mname = "A";
     fname = fname + " " + mname + ". " + lname;

     fullName = fname;

     cout << "Fill Name is : "<<fullName<<endl;

     if(fname == fullName)
        cout<<"But the names remain the same\n";
     else
        cout<<"Why did you change your name?\n";

     fname = "Mary";
     if(fname == fullName)
        cout<<"But the names remain the same\n";
     else
        cout<<"Why did you change your name?\n";

     for(int index = 0; index < fullName.length(); index++)
        cout << fullName[index] << endl;
  return 0;
 }

 Here is my header file:

    #ifndef _MYSTRING
#define _MYSTRING
#include <iostream>

using namespace std;

class MyString
{
    private:

        int size;
        int capacity;
        char *data;

    public:

        MyString();
        MyString(char *);
        MyString (const MyString&);
        ~MyString();
        MyString operator =(const MyString &);
        MyString& append (const MyString&);
        MyString& erase();
        MyString operator + (const MyString&) const;
        bool operator == (const MyString&);
        bool operator < (const MyString&);
        bool operator > (const MyString&);
        bool operator <= (const MyString&);
        bool operator >= (const MyString&);
        bool operator != (const MyString&);
        void operator += (const MyString&);
        char& operator [] (int);
        void getline (istream&);
        int length () const;
        friend ostream& operator<< (ostream&, MyString&);
        void grow();
};

#endif

Here are my functions:

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

using namespace std;

MyString :: MyString()
{
    size = 0;
    capacity = 1;
    data = new char[capacity];
    data[0] = '\0';
}

MyString :: MyString(char * s)
{
    size = strlen(s);
    capacity = 1;
    data = new char[capacity];
    while (size >= capacity)
    {
        grow();
    }
    strcpy(data, s);
    data[size + 1] = '\0';
}

MyString :: MyString (const MyString& s)
{
    size = s.size;
    capacity = 1;
    data = new char[capacity];
    while (size >= capacity)
    {
        grow();
    }

    strcpy(data, s.data);
    data[size + 1] = '\0';
}

MyString :: ~MyString()
{
    delete []data;
}

 MyString MyString :: operator =(const MyString& s)
{
    delete [] data;

    size = s.size;
    capacity = 1;
    data = new char[capacity];
    while (size >= capacity)
    {
        grow();
    }

    strcpy(data, s.data);
    data[size + 1] = '\0';
    return *this;
}

MyString& MyString :: append (const MyString& s)
{
    size += s.size;
    while(size >= capacity)
    {
        grow();
    }
    strcat(data, s.data);
    data[size + 1] = '\0';
    return *this;
}

MyString& MyString :: erase()
{
    size = 0;
    data[0] = '\0';
    return *this;
}

MyString MyString :: operator + (const MyString& s) const
{
  char *addition;
  addition = new char[strlen(data) + strlen(s.data)];
  strcpy(addition, strcat(data, s.data));
  addition[size] = '\0';
  return addition;
}

bool MyString :: operator == (const MyString& s)
{
  if (strcmp(data, s.data) == 0)
  {
  return true;
  }

  else
  {
  return false;
  }
}

bool MyString :: operator < (const MyString& s)
{
  if (strcmp(data, s.data) < 0)
  {
  return true;
  }

  else
  {
  return false;
  }
}

bool MyString :: operator > (const MyString& s)
{
  if (strcmp(data , s.data) > 0)
  {
  return true;
  }

  else
  {
  return false;
  }
}

bool MyString :: operator <= (const MyString& s)
{
  if (strcmp(data, s.data) <= 0)
  {
  return true;
  }

  else
  {
  return false;
  }
}

bool MyString :: operator >= (const MyString& s)
{
  if (strcmp(data, s.data) >= 0)
  {
  return true;
  }

  else
  {
  return false;
  }
}

bool MyString :: operator != (const MyString& s)
{
  if (!strcmp(data, s.data))
  {
  return true;
  }

  else
  {
  return false;
  }
}

void MyString :: operator += (const MyString& s)
{
  size += s.size;
  capacity = 1;
    while(size >= capacity)
    {
        grow();
    }
    strcat(data, s.data);
    data[size] = '\0';
}

char& MyString :: operator [] (int n)
{
  return data[n];
}

void MyString :: getline (istream& in)
{
    size = 0;
    char c;
    in.get(c);
    while(c != '\n' && in)
    {
        data[size] = c;
        size++;
        if (size >= capacity)
        {
            grow();
        }
        in.get(c);
    }
    data[size] = '\0';
}

void MyString :: grow()
{
    char *temp;
    temp = data;
    data = new char[capacity];
    strcpy(data, temp);
    data[size] = '\0';
    delete [] temp;
}

int MyString :: length () const
{
    return size;
}

ostream& operator<< (ostream& out, MyString& m)
{
  out << m.data << endl;
  return out;
}