// Mr. Minich
// CMPSC 101
// Ch. 3 Demo Program #3
// January 30, 2000 
// Purpose - to illustrate promotion (implicit type conversion) and typecasting (explicit type conversion)

#include <iostream>
using namespace std;

int main()
{
	int int1 = 1;       // int1 is declared and initialized in one statement 
    	int int2 = 2;                   
	int int3;			// int3 is not initialized
	double double1;
 	double double2 = 2.0;

	int3 = int1 + int2; 		// int3 = 3 (the whole number)
	cout << "int3 = " << int3 << endl;

	double1 = int1 + double2; 	// double1 = 3.0 (the decimal number)

	// this is an example of promotion, where C++ automatically
	// promotes int1 (the whole number) to the double type in order
	// to be able to perform the addition of two doubles. Technically,
	// C++ cannot add an int to a double even though both are 4-bytes.

	cout << "double1 = " << double1 << endl;

	double2 = 1999.99;
	cout << "The price of the computer is $" << double2 << endl;

	cout << "The price of the computer is $" << int (double2) << endl;

	// typecasting is used here by the programmer to 
	// force C++ to interpret double2 as an integer
	// resulting in the truncation of the value 1999.99 to simply 1999

	// Summary: Promotion is automatically used by the compiler
	// to evaluate expressions while typecasting is explicitly
	// used by the programmer for whatever reason. Typecasting and 
	// promotion are examples of mixing data types.

	return 0;
}// end of main