12.9 ArraySubscriptOperator_MyString.cpp

#include <iostream>
#include <string>
#include <string.h>
using namespace std;

class MyString
{
private:
   char* Buffer;
   
   // private default constructor
   MyString() {}

public:
   // constructor
   MyString(const char* InitialInput)
   {
      if(InitialInput != NULL)
      {
         Buffer = new char [strlen(InitialInput) + 1];
         strcpy(Buffer, InitialInput);
      }
      else 
         Buffer = NULL;
   }

   MyString operator + (const char* stringIn)
   {
      string strBuf(Buffer);
      strBuf += stringIn;
      MyString ret(strBuf.c_str());
      return ret;
   }

   // Copy constructor
   MyString(const MyString& CopySource)
   {
      if(CopySource.Buffer != NULL)
      {
         // ensure deep copy by first allocating own buffer 
         Buffer = new char [strlen(CopySource.Buffer) + 1];

         // copy from the source into local buffer
         strcpy(Buffer, CopySource.Buffer);
      }
      else 
         Buffer = NULL;
   }

   // Copy assignment operator
   MyString& operator= (const MyString& CopySource)
   {
      if ((this != &CopySource) && (CopySource.Buffer != NULL))
      {
         if (Buffer != NULL)
          delete[] Buffer;

         // ensure deep copy by first allocating own buffer 
         Buffer = new char [strlen(CopySource.Buffer) + 1];

         // copy from the source into local buffer
         strcpy(Buffer, CopySource.Buffer);
      }

     return *this;
   }

   const char& operator[] (int Index) const
   {
      if (Index < GetLength())
         return Buffer[Index];
   }
  
   // Destructor
   ~MyString()
   {
      if (Buffer != NULL)
         delete [] Buffer;
   }

   int GetLength() const
   {
      return strlen(Buffer);
   }

   operator const char*()
   {
      return Buffer;
   }
};

int main()
{
   cout << "Type a statement: ";
   string strInput;
   getline(cin, strInput);

   MyString youSaid(strInput.c_str());

   cout << "Using operator[] for displaying your input: " << endl;
   for (int index = 0; index < youSaid.GetLength(); ++index)
      cout << youSaid[index] << " ";
   cout << endl;

   cout << "Enter index 0 - " << youSaid.GetLength() - 1 << ": ";
   int index = 0;
   cin >> index;
   cout << "Input character at zero-based position: " << index;
   cout << " is: " << youSaid[index] << endl;

   return 0;
}