Enter an integer: 12 The number 12 is zero or positive Good-bye for now
The false branch is executed because the answer to the
question num < 0
was false.
Here is the number tester implemented as a program:
import java.util.Scanner;
public class NumberTester
{
public static void main (String[] args)
{
Scanner scan = new Scanner( System.in );
int num;
System.out.println("Enter an integer:");
num = scan.nextInt();
if ( num < 0 )
System.out.println("The number " + num + " is negative");
else
System.out.println("The number " + num + " is zero or positive");
System.out.println("Good-bye for now");
}
}
The words if
and else
are markers that divide the
decision into two sections.
The else
divides the true branch from the
false branch.
The if
is followed by a question enclosed in parentheses.
The expression num < 0
asks if the
value in num
is less than zero.
if
statement always asks a question (often about a variable).
Notice that a two-way decision is like picking which of two roads to take
to the same destination.
The fork in the road is the if
statement, and the two roads come together
just after the false branch.
The user runs the program and enters -5
.
What will the program print?