A simple program I did for completing an exercise:

Code:
 //This program reads the <char> from the keyboard,  and then displays one of the following messages:/* 1. If <char> is a lower case letter, the message is 
           "The upper case character correspond to <char> is ___. "
   2. If <char> is an upper case letter, the message is
           "The lower case character correspond to <char> is ___. "
   3. If <char> is not a letter, the message is
           "<Char> is not a letter.                                                                      */




#include <iostream>


using namespace std;


int main()
{


  char letter;


  //prompt the user for letter




  cout << "Type in any letter:\n";
  cin  >> letter;
  cout << "\n";


  //print the appropriate message


  if (letter >= 65 && letter <=90) 
         cout << "The lower case character corresponds to '" << letter <<"' is " << (char)(letter + 32) <<".\n";


  else if (letter >= 97 && letter <=122) 
         cout << "The upper case character corresponds to '" << letter <<"' is " << (char)(letter - 32) << ".\n";


  else 
         cout << "The character '" << letter <<"' is not a letter.\n";


  system("pause");


  return 0;


}

Notice that I put
char letter;
However, the example answer given for the question number 3 @ C++ EXERCISES 2 is
this http://www.doc.ic.ac.uk/~wjk/C++Intr...illerEA2-3.cpp.

Can you please tell me why he/she alter the line to this??

char letter = 'a';
Thank you.