C String and C++ Strings: Similarities and Differences

I came across this scenario recently when a C style string (as some people refer to char[] as) had to be compared to a C++ string and even though this is straightforward, i fell in the same trap as a lot of people about forgetting that there is a Nul charachter as the end of C style string. Anyway, here is an example to demonstrate both the strings.

//Program tested on Microsoft Visual Studio 2008 - Zahid Ghadialy
//Program to demonstrate length and size of char* and string
//and to show similarity and difference between them
#include<iostream>

using namespace std;

int main()
{
  cout<<endl;
  char a[10]="Hello";
  cout<<"Size of a = "<<sizeof(a)<<endl;
  a[5]='\0'; //Terminating the C string in between with Nul character
  cout<<"Size of a = "<<sizeof(a)<<endl;

  cout<<endl;
  char b[]="Hello";
  cout<<"Size of b = "<<sizeof(b)<<endl; //Note the size
                                         //Automatic Nul charachter added

  cout<<endl;
  string c("Hello");
  cout<<"Size of c = "<<sizeof(c)<<endl;
  cout<<"Length of c = "<<c.length()<<endl;

  c += " Zahid";
  cout<<"Size of modified c = "<<sizeof(c)<<endl;
  cout<<"Length of modified c = "<<c.length()<<endl;

  //Add an extra NULL charachter
  cout<<endl;
  char d[]="Hello\0";
  cout<<"Size of d = "<<sizeof(d)<<endl;
  for(int i = 0; i < sizeof(d); i++)
  {
    cout<<"d["<<i<<"] = "<<d[i]<<endl;
  }

  //When is a char[] similar to string?
  cout<<endl;
  char e[]="Zahid";
  string f = "Zahid\0";
  const char* temp = f.c_str();
  if(strcmp(e , temp) == 0)
  {
    cout<<"e == f"<<endl;
  }
  else
  {
    cout<<"e != f"<<endl;
  }

  return 0;
}

The output is as follows: