9. Outline of a Two-way Decision


Answer:

    Enter an integer:
    17
    The number 17 is zero or positive.
    Positive numbers are greater than zero.
    Good-bye for now

The false block was executed because the answer to the question (num < 0) was false.
The false block consists of three statements.

Outline of a Two-way Decision


Here is an outline of a two-way decision structure:

// statements that are executed before the decision

if ( condition )
// true branch

else
// false branch

// statements that are executed after the branches join together again

Here are some details:

      • The condition evaluates to true or false, often by comparing variables and values.
      • The else divides the true branch from the false branch.
      • The statements after the false branch are always executed.
      • A block consists of several statements inside a pair of braces, { and }.
      • The true branch can be a block.
      • The false branch can be a block.
      • There can be as many statements in a block as you need.
      • When a block is chosen for execution, the statements in it are executed one by one.

The condition can compare what is held in a variable to other values. You can use the comparisons <>, and so on. (More about these later.) The first statement after the false branch will be executed no matter which branch is chosen. The if-else is like a fork in the road, but the road always comes together again.


Question 9:

Is the following section of a program correct?

    if ( num < 0 ) System.out.println("The number " + num + " is negative."); else System.out.println("The number " + num + " is zero or positive."); System.out.print ("Positive numbers are greater "); System.out.println("than zero. "); System.out.println("Good-bye for now");