Repeating Actions

What will we learn today? Repeated Actions Need for Repetition Repetition with Loop Nested Loops

Repeated Actions in Real Life Consider those daily actions When we talk, we simply open and close our months repeatedly a counted number of times When we walk, we move our legs forward and backward as we move a counted number of steps

Need for Repetition Consider a situation in which a man walks 5 steps forward towards a palm tree The man’s legs walk a step with each meter that he moves forward (if man moves forward 5 meters, his legs walking occur 5 times) One possible way is to animate 5 steps But, what if we want to repeat the walking action 20 times (becomes tedious and boring, isn’t it??) We can use clipboard. But it will be a bit tedious copying and dragging block of instruction several number of times

Repetition with Loops An easy way to do this is by using a loop statement The Loop Statement Is a simple way to repeat an action a counted number of times Is used to execute a block of instructions again and again (limited number of times) Is quick and easy to write and also easy to understand A count is used to describe the number of times a loop/action(s) repeats

Hide and Seek Example with Loops Remember the “hide and seek” example we did in the methods lecture Remember how many times we had to animate(copy and past) the actions Painful and tedious wasn’t it!!! Now, the torture is over and we will use loops to make our lives simpler

Repetition with Loop We have repeated actions in ‘Turn Around’ methods and in the ‘world.myfirst’ method To create a loop in a program Drag a loop tile into the editor inside the do-in order block of ‘world.myfirst’ method Choose other and enter number 3 in the popup menu Drag the ‘world.seekCat’ method into the loop statement Inside the do-together block make two loops for the turning around methods A loop can be executed only a whole number of times

Nested Loops A loop can be nested inside another loop (a loop is placed inside other loop) Remember, the ‘move around’ method was used to make a complete turn around the tree (which requires repeating the moving a step and turning right actions ten times) To make 3 complete turns we need to repeat the previous action 3 times Loop 3 times Loop 10 times Move Around

Nested Loop The second loop ‘Loop 10 times’ is called a nested loop It will fully execute each time the outer loop ‘loop 3 times’ executes once The count of the outer loop is 3, and the count of the inner loop is 10 The inner loop will execute 10 times for each of the 3 executions of the outer loop The moving around action will occur 30 (3*10) times in total Loop 10 times Move Around

The Result Loop Statement

Turn Around methods with Loops

Let’s Work with Alice Write an animation where an Arabian man in his tent serves coffee to his guests Create a method ‘fill-inCups’ in which the host man holding the dallah (middle east) and fill-in 3 empty cubs in the tray (loop 3 times) Create a method ‘serveCoffee’ where the host man serves his guests (loop 2 times) Develop the animation for this story