////////////////////////////////////////////////
//  data.cpp - how do I declare and use data? //
////////////////////////////////////////////////
#include <iostream>
using namespace std;

// Data is declared by:
//   - stating a type, perhaps with qualifiers like const, 
//   - stating an identifer, e.g., a name
//   - optionally specifying an array of fixed size
//   - optionally specifying initializing value(s)

void main() {

// simplest data declaration
  
  int x;
  x = 3;
  cout << "\n  x is: " << x << ", ";
  cout << ++x << ", ";
  cout << (x=x+1) << endl;

// using a type qualifier, e.g., const
  
  const double PI = 3.1415927;
  cout << "\n  PI is: " << PI << endl;

// defining an array using the type qualifier unsigned
// and initializing values

  unsigned char cArr[5] = { 'a', 'e', 'i', 'o', 'u' };
  cout << "\n  vowels are: ";
  int i;
  for(i=0; i<4; i++)
    cout << cArr[i] << ", ";
  cout << cArr[4] << "\n\n";
}