//SqrtIfApplet.java
//demo of if statement

import javax.swing.*;

public class SqrtIfApplet extends JApplet {

    public void init() {
	String input;
	double num, numSqrt;

	input = JOptionPane.showInputDialog( "Enter a number" );
    	num = Double.parseDouble( input );

	if (num >= 0) {
	    numSqrt = Math.sqrt(num);
	    JOptionPane.showMessageDialog(null, "Square root = " + numSqrt ); 
	}
	else
	    JOptionPane.showMessageDialog(null, "No square root of negative number"); 
	    
    }	
} 

/*
if statement makes the program branch, either the true branch or the 
false (else) branch is executed, not both and not neither, the other
branch is skipped.  Question is asked, decision is made, one branch is selected.  
Based on language/logic/real life: IF it's raining then I'll stay in,
                                   otherwise I'll go out.
Syntax: 
   if (booleanExpression) {
     statement(s)   //of true branch
   }
   else {
     statement(s)   //of false branch
   }
If more than one statement, must be in {}  (If only one statement, braces 
are not required.)  
Without braces, only single following statement
is part of the if or else part, causing either syntax error or bug.
else part is optional.  Can not have else without matching if.
Notice NO ; on if line!
booleanExpression is an expression that evaluates to true or false.
 Exs: num<=0     num==0     num!=0     num>10    num1==num2   num1>=num2

*/