Loops
Loops are a category of control blocks, shown in Fig. 58, that direct the flow of a program. They run the nested action blocks a number of times in accordance with the test taken at the beginning of the Loop.
Fig. 58 The palette of KookaBlockly Loop blocks
Loop Repeat
This block runs the blocks nested inside of it for the specified number of times.
The number of iterations is provided by an input from a numeric value block which can contain a fixed number (from the Math blocks category), a numeric computation (using blocks from the Math blocks category), or a variable. See also the Variables category.
When the iterations of the Loop are complete the program moves on to the blocks below it.
Loop Repeat While / Until
In this block the two operations of While and Until are very similar to each other. Both require a Boolean
True / False value block in their input socket.
Repeat While will continue as long as the input value block is True.
Repeat Until will continue as long as the input value block is False.
Count With Variable From-To-By
This Loop will run its nested blocks several times depending upon the input numbers given.
The Loop will start by setting the chosen variable to its starting value using the first input.
Each time the Loop completes (known as an iteration), the variable’s value is changed by the number in the third input.
The Loop will continue to iterate until the value of the variable is equal to or greater than the number in the second input.
So if the Loop is configured to run from 0 to 3 by 1, it would run the nested blocks with the variable’s
value being 0, 1 and 2. Then the program would advance to the next block after the
Loop. During the Loop, the variable’s value indicates which repetition of the Loop is being run and can be used in calculations.
The variable drop-down list contains the names of the available variables. The default variables are i and j.
The options Rename variable and Delete variable are configuration functions to manage the creation of new variables or deletion of existing variables. See also the Variables Category.
Count With Variable Example
In Fig. 59 is an example of the Loop counting between 1 and 16 by 3.
Fig. 59 Example script counts from 1 to 16
On each iteration of the Loop, the value of the variable i is printed on a new line on the display, as shown in Fig. 60.
For Each Item In List
This block has an input socket that takes a List. See the Lists Category.
The Loop begins by setting the chosen variable to be the same as the first item from the List and then it runs the nested blocks.
The Loop then sets the chosen variable as the second item of the List and runs the nested blocks again.
The Loop repeats until it has run once for every item from the List.
This type of Loop is useful for printing a List of text items in subsequent lines on the Display, or for processing a List of readings gathered from sensors.
Break / Continue Loop
This block must be placed inside a Loop. If the block is not placed in a Loop it will turn white with a warning symbol - see Fig. 62.
Fig. 61 The Loop Breakout / Continue used in a Loop
This block is used to either break out of the Loop, or to stop the current iteration of a Loop.
break out immediately ends the Loop and jumps to the next block after the Loop.
continue with next iteration stops the current iteration and jumps back to the top of the Loop and will run again if the Loop allows it.
The usual way to use this block is in an If-Do block where breaking a Loop is subject to a logical test as in Fig. 61.
Fig. 62 The Warning appearance of the Loop Breakout / Continue block when not inside a Loop