If Then Blocks

if / else blocks are a way for your robot to make decisions during a project.

Understanding if / else blocks

The if then branch

An if/else block has two parts. In the if then branch, you insert a Boolean block into the condition slot for the robot to check.

The else branch

In the else branch, you add the blocks you want to run when the condition is false.

Insert a Boolean block

Drag a Boolean block into the empty condition slot in the if then branch.

All Boolean blocks have sharp edges and a question mark in its name, such as the controller button pressed? block.

If the condition is true

If the condition is true, the blocks inside the if then branch will run.

If the condition is false

If the condition is false, the blocks inside the else branch will run.

Repeating if / else blocks

An if/else block only checks its condition once. If you want the condition to be checked repeatedly, put the if/else block inside a looping block, like forever.

An if/else block nested inside a forever block.

    forever
        if <[Controller1 v] [▲ v] pressed?> then
            drive [forward v]
        else
            stop driving
        end
    end

The if Block

The if block is only the if then branch. If the condition isn’t true, nothing will happen.

The if block.

    if <[Controller1 v] [▲ v] pressed?> then
        drive [forward v]
    end

The if / else if / else Block

The if / else if / else block can be used to test multiple conditions one after another. It can be expanded to test as many conditions as needed.

An if/else if/else block, testing three Controller buttons.

    if <[Controller1 v] [◀ v] pressed?> then
        turn [left v] for (90) degrees ▶
    else if <[Controller1 v] [▶ v] pressed?> then
        turn [right v] for (90) degrees ▶
    else if <[Controller1 v] [A v] pressed?> then
        stop driving
    else
        drive [forward v]
    end