1D: Loops

Make sure that your CoDrone Mini is paired before starting the lesson! If you forgot how to do this, make sure to review how to pair to Blockly here.

Loops let you repeat sections of your code. They’re a great shortcut — without them, you might have to connect the same blocks over and over again, which can leave a lot of room for error.

Take a look at our example. If it’s familiar, it’s because you probably had something just like it for your challenge code in the variables lesson! Without a loop, this code is 14 blocks long…

…but with a loop, it’s half the size at 7 blocks! Although it’s shorter, it does the same thing and works just as well.

A big part of programming is making sure your code is easy for others to understand. Loops do just that by making your code shorter and simpler.

Blockly has three different types of loops:

• For loops will repeat the code inside them for the number of times you choose. There are two blocks you can use to do this! Note: in Blockly, these blocks look like “repeat _ times” or “count with”, but are still considered for loops.
• While loops will repeat the code inside them while a certain condition that you set is true.
• Until loops will repeat the code inside them until a certain condition that you set is true.

For loops repeat the code that’s inside them for the number of times that you choose. Once the code has been repeated for that amount of time, your program will exit out of the loop and move on to the next block.

Like we said in the second step, there are two for loop blocks in Blockly! One is the repeat for _ times block. To change the number in that block, you can just type in a new value. If you want to use a mathematical operation, equation, or variable, you can drag blocks from the math, logic, or variables menus to that gray area within the loop block.

The other for loop block is a little more complicated and looks more like what you would see in text-based coding. With this block, you name a variable, and then you set it to start at one number and go up to another. You can also set how much you want the value to increase by.

Ready to try for loops out? Program your CoDrone Mini to look like it’s flying up a flight of stairs! The catch: since there are two different for loop blocks, you will need to write two different programs to try them out. Your CoDrone Mini should keep moving forward and up. The programs might look different to you, but what happens when you run them?

While loops repeat the code that’s inside them while the condition that you set is true. Each time the program runs through the while loop, it checks to see if the condition is true. If it is not, your program will exit the loop.

You had your drone fly in a shape in the variables lesson, but now you can try it with a loop! Set your variable to 0, and then have it increase by 1 every time in the while loop. While your variable is less than or equal to 4, program your CoDrone Mini to fly forward and then turn (or vice versa).

Wondering why you’re starting at 0? Humans begin counting at 1, but computers begin counting at 0!

You can program a while loop to run like a forever loop, which will repeat the code inside of it forever! Connect a “code is running” block to the while condition. It’s in the “Status Checkers” category. This block makes sure that your code will stop when you press the “Stop” button. Don’t worry that you haven’t seen the LEDs before — you will have an entire lesson about them later.

You may notice that the colors are switching very quickly. Add some wait blocks from the timing section in between switching colors.

Until loops are a lot like while loops, except they’ll run the code inside the block until the condition is true. Each time the program runs through the while loop, it checks to see if the condition is true. If it is, the program will exit the loop, but after it finishes running that block of code one last time.

Set your variable to 0, and then have it increase by 1 every time in the while loop. Program your drone so that until your variable gets to 8, it will turn left for 2 seconds at 50% power.

Challenge: Digital Figure 8

Have your drone fly in a digital figure eight, like the one pictured, using loops! Hint: you will most likely need to have two separate loops for this so both halves of the eight are included.