1. Making Decisions in Programs with Conditional Statements

Let's imagine that we want to write a program for an amusement park ride to check a person's height. If they're 48 inches or taller, the program will display a "you're tall enough" message. 

To make decisions like this in our programs, we use a conditional statement. It's called a "conditional" statement because the decision depends on a condition. It is also sometimes called a selection statement, because it is selecting which parts of the code to execute. In the example above, the condition is whether the user's height is greater than 48 inches or not.

Conditional statements are also called if statements, because they use the word "if": if the height is greater than or equal to 48, then display the message. But otherwise don't display it.

2. The if Block

In RoboBlocky we use the if block for a basic conditional statement, found in the Logic menu:

We combine it with the relational operators block (also in the Logic menu):

Click on the = sign to get the menu with the relational operator choices:

The next section shows how to put it all together.

3. Example: Checking the Height

Here's how we would write the program to check a person's height. It prompts the user to enter their height and then displays a message if they're 48 inches or taller:

Here's what the code does, in order:

1. Creates a variable named height and sets its value to 0.
2. Displays the sentence "How tall are you in inches?"
3. Inputs the user's entry into the height variable.
4. Uses an if statement to check whether the value of height is greater than or equal to 48. If it is, the "You're tall enough" message is displayed and then "All done". If the height is not greater than 48, then it skips the code in the if statement and just displays "All done".

Run the code in Example 1 several times to see how it works. Try entering values for the height that equal 48, are greater than 48, and are less than 48.

Example 2 uses a conditional statement to move the robot if a random number comes up even.