/*
    identifier.cpp program to illustrate acceptable variale names.

    See Nyhoff P47
    
    Rule for variable names:
     * can only contain the following letters: a-z A-Z 0-9 and _
     * names are case sensitive
     * must not match C++ keywords such as int, double, for, while ...        
       
*/

#include <iostream>
using namespace std;

int main()
{                                                                // program starts here
   int i;                                                        // often i,j,k,n,m are used for loop variables. 
   int number=40000000;

   int LifeTheUniverseAndEverything=42;
   int lifetheuniverseandeverything=43;                          // note variables are case sensitive

   int Life_The_Universe_And_Everything=44;
   int VilliliIili1l1lIi1l1i=101                                 // Horrible but acceptable name..
   
// Const tells the compiler that the following value is a constant, it allows the compiler to replace
// all occurances of the variable with the corresponding number. The compiler also generate an error
// if a constant is changed.    
   
   const double PI=3.14159265;                                   // PI is now a constant, and can't be changed.
   const double SPEED_OF_LIGHT=299792458.00;                     // speed of light
   
   return 0;
}                                                                // program ends here