//LogicalOperatorsTest.java

/* logical operators examples.
if sunny OR weekend  then go outside
if sunny AND weekend  then go outside
if NOT rainy   then go outside


 two truth values ||'ed together are True if either or both are True.
  Ex.      booleanExpr1 || booleanExpr2
   Is True if booleanExpr1 is True or if booleanExpr2 is True (or if
   both are True).  
   Is False only if both are False.

 two truth values &&'ed together are True only if both are True.
  Ex.      booleanExpr1 && booleanExpr2
   Is True if booleanExpr1 is True and booleanExpr2 is True. 
   Is False if either or both are False.

 a truth value !'ed reverses its truth value.
  Ex.  !booleanExpr
   Is True if booleanExpr is False
   Is False if booleanExpr is True

*/

import javax.swing.*;

public class LogicalOperatorsTest extends JApplet {

    public void init () {
	String input;
	int monthNum;
	int days=0;
	int num, b, d;
	
	//test if a variable is either of two values
	input = JOptionPane.showInputDialog("Enter a 2 or a 5");
	num = Integer.parseInt(input);
	if (num==2 || num==5)
	    JOptionPane.showMessageDialog(null, "good number: is 2 or 5" + num);
	else
	    JOptionPane.showMessageDialog(null, "bad number: " + num);

	//*****
	String language;
	language = JOptionPane.showInputDialog("Enter language (english or spanish)");
	if (language.equals("english") || language.equals("spanish"))
	    JOptionPane.showMessageDialog(null, "good language: " + language);
	else
	    JOptionPane.showMessageDialog(null, "bad language: " + language);
	
	//*****
	input = JOptionPane.showInputDialog("Enter month number");
	monthNum = Integer.parseInt(input);
	// 2 or more truth values ||'ed together is True if one or more are True.	
	if (monthNum==1 || monthNum==3 || monthNum==5 || monthNum==7 ||
	    monthNum==8 || monthNum==10 || monthNum==12) 
	    days = 31;
	else if (monthNum==4 || monthNum==6 || monthNum==9 || monthNum==11)
	    days = 30;
	else if (monthNum == 2)
	    days = 28;
	else
	    JOptionPane.showMessageDialog(null, "invalid month number");
	
	JOptionPane.showMessageDialog(null, "days= " + days);
	
	//*****
	//test if number in a range of values
	input = JOptionPane.showInputDialog("Enter a number between 5 and 10");
	num = Integer.parseInt(input);
	if (num>=5 && num<=10)
	    JOptionPane.showMessageDialog(null, "in range: " + num);
	else
	    JOptionPane.showMessageDialog(null, "out of range: " + num);
	
	//test if number not in a range of values
	if (num<5 || num>10)  //logical reverse of above condition
	    JOptionPane.showMessageDialog(null, "out of range: " + num);
	else
	    JOptionPane.showMessageDialog(null, "in range: " + num);
	
	//we say "num not 2 or it's not 5", but that means in logic:
	//num not 2 AND it's not 5.  We don't speak logically correctly.
	input = JOptionPane.showInputDialog("Enter a 2 or a 5");
	num = Integer.parseInt(input);
	if (num!=2 && num!=5)  //logical reverse of above condition
	    JOptionPane.showMessageDialog(null, "bad number: is not 2 nor 5 " + num);
	else
	    JOptionPane.showMessageDialog(null, "good number: " + num);


	language = JOptionPane.showInputDialog("Enter language (english or spanish)");
	// ! is logical NOT, reverses truth/boolean value
	if (!language.equals("english") && !language.equals("spanish"))
	    JOptionPane.showMessageDialog(null, "bad language: not English nor Spanish" + language);
	else
	    JOptionPane.showMessageDialog(null, "good language: " + language);

	//enter two numbers for denominators, 
	input = JOptionPane.showInputDialog("Enter a number");
	b = Integer.parseInt(input);
	input = JOptionPane.showInputDialog("Enter a number");
	d = Integer.parseInt(input);
	//check if either is zero:
	if (b==0 || d==0)
	    JOptionPane.showMessageDialog(null, "bad denominator(s)");
	else
	    JOptionPane.showMessageDialog(null, "good denominators");
	//check that neither is zero:
	if (b!=0 && d!=0)    //reverse of above.  swap if and else parts
	    JOptionPane.showMessageDialog(null, "good denominators");
	else
	    JOptionPane.showMessageDialog(null, "bad denominator(s)");
    }
}
/*
Wrong wrong wrong:
 num==2 || 5
 num==2 || ==5
 num==1 || 2 || 3
 num!=2 && 5
 num!=2 && !=5
 num<5 || 10
 num<5 || >10
 5<=num<=10

 num!=2 || num!=5     always True, so is useless and wrong 
 num==2 && num==5     always False, so is useless and wrong 
*/