// File: CharTest.java

// CharTest class shows that primitive chars are stored as integers (16-bit).

// When mixing ints and chars in an expression, the result is "promoted" to
// type int (the "higher" type), and can be explicitly converted to char

// Also shows String methods charAt() and length(), and static Character class 
// methods toUpperCase() and toLowerCase()

public class CharTest
{
	public static void main (String [] args)
	{
		char letter ;
		int number ;
		
		letter = 'A' ;		// letter gets 65
		number = 66 ;
		
		System.out.println("After assigning 'A' to letter, 66 to number...") ;
		System.out.println("letter: " + letter + "\tnumber: " + number) ;
		
		// print mixed expression: letter + number
		System.out.println("\nAdding letter + number, result is " + 
		                   (letter + number) ) ;
		 
		number = number - 'A' ;
		System.out.println("\nAfter assignment:  number = number - 'A' ;" +
		                   "\nnumber is: " + number) ;

		letter++ ;	// increment letter by 1
		System.out.println("\nAfter autoincrement: letter++ ; " 
		                   + "\nletter is: " + letter) ;
		
		// this will not compile: letter = letter + 1
		
		// to convert mixed expression to char, need explicit cast
		letter = (char)(letter + 1) ;
		System.out.println("\nAfter assignment:  letter = (char)(letter + 1) ; " 
		                   + "\nletter is: " + letter) ;
		
		letter = 97 ;
		number = '?' ;	// implicitly converted to int 63
		
		System.out.println("\nAfter assigning 97 to letter, '?' to number...") ;
		System.out.println("letter: " + letter + "\tnumber: " + number) ;

		// demonstrate the charAt method
		
		String greeting = "Hello!" ;
		System.out.println("\nString greeting = \"Hello!\"") ;

		// get and print first char
		letter = greeting.charAt(0) ;
		System.out.println( "\ngreeting.charAt(0) returns: " + letter ) ;
		
		// get and print 2nd char
		letter = greeting.charAt(1)	;
		System.out.println( "greeting.charAt(1) returns: " + letter ) ;
		
		//get and print last char
		letter = greeting.charAt( greeting.length()-1 ) ;
		System.out.println( "greeting.charAt( greeting.length()-1 ) returns: " 
		                    + letter ) ;
		// static Character class methods toUpperCase and toLowerCase
		
		letter = Character.toUpperCase('q') ;
		System.out.println( "\nCharacter.toUpperCase('q') returns: " + letter) ;
		letter = Character.toUpperCase('H') ;
		System.out.println( "Character.toUpperCase('H') returns: " + letter) ;
		letter = Character.toUpperCase('*') ;
		System.out.println( "Character.toUpperCase('*') returns: " + letter) ;
		
		letter = Character.toLowerCase('q') ;
		System.out.println( "\nCharacter.toLowerCase('q') returns: " + letter) ;
		letter = Character.toLowerCase('H') ;
		System.out.println( "Character.toLowerCase('H') returns: " + letter) ;
		letter = Character.toLowerCase('*') ;
		System.out.println( "Character.toLowerCase('*') returns: " + letter) ;
	}
}

/*  program output
 
After assigning 'A' to letter, 66 to number...
letter: A       number: 66

Adding letter + number, result is 131

After assignment:  number = number - 'A' ;
number is: 1

After autoincrement: letter++ ;
letter is: B

After assignment:  letter = (char)(letter + 1) ;
letter is: C

After assigning 97 to letter, '?' to number...
letter: a       number: 63

String greeting = "Hello!"

greeting.charAt(0) returns: H
greeting.charAt(1) returns: e
greeting.charAt( greeting.length()-1 ) returns: !

Character.toUpperCase('q') returns: Q
Character.toUpperCase('H') returns: H
Character.toUpperCase('*') returns: *

Character.toLowerCase('q') returns: q
Character.toLowerCase('H') returns: h
Character.toLowerCase('*') returns: *

*/