Have yertle draw an equilateral triangle using a loop. Use the Active Code window below or this link to have yertle draw the following shapes using loops. In the last exercise, you used a for-loop to have the turtle draw a square. Programming Challenge : Turtles Drawing Shapes ¶ "Should only need forward() void test3()Ĥ.2.4. Int count = countOccurences(code, forwards) Change the following code to use a for loop to draw the squareīoolean passed = checkCodeContainsRegex("for loop", void test2() (If the code below does not work for you, you can copy the code into this link (refresh page after forking and if it gets stuck) or download the files here to use in your own IDE.)Ĭan you change the code below to remove the repeated lines of code and use a loop to draw 4 sides of the square? Whenever you find yourself repeating code, try to use a loop instead! Can you change the code below to remove the repeated lines of code and use a loop to draw 4 sides of the square? Did you notice that the code becomes a lot shorter? You should only need 1 call to forward and 1 call to turn in the loop. Public class RunestoneTests extends void testMain() throws IOExceptionīoolean passed = getResults(expect, output, "Expected output from main") ĭo you remember when we used the turtle objects to draw shapes? To create a square without loops we had to repeat code to go forward and turn 90 degrees to the right 4 times like below. When the value in i is equal to 0 the loop stops executing.Ĭan you make the loop count by 2s backwards? It should print out 5 3 1? Remember to change all 3 parts of the for loop. Before the condition is checked again, i is decreased by 1. Since 5 is greater than 0, the body of the loop executes. It initializes the value of the variable i equal to 5 and then checks if i is greater than 0. The method printPopSong prints the words to a song. Passed = getResults(expect1, output1, "Do not start loop from 5", passed) String expect = "5 bottles of pop on the wall" īoolean passed = !ntains(expect) Passed = getResults(expect1, output1, "Print the song from 3", void testMain2() throws IOException String expect = "3 bottles of pop on the wall" īoolean passed = ntains(expect) String line3 = "Take one down and pass it around" String line1 = " bottles of pop on the wall" What do you think will happen when you run the code below? How would it change if you changed line 11 to initialize i’s value to 3? Try the Code Lens button to visualize and trace through this code. String target = "for (int * = # * ? # *~)" īoolean passed = checkCodeContainsRegex("for loop", target) Public void testMain() throws IOExceptionīoolean passed = getResults(expect, output, "Running void testWhile() throws IOExceptionīoolean passed = checkCodeNotContainsRegex("while loop", void testFor() throws IOException Public class RunestoneTests extends CodeTestHelper Can you change it to a for-loop? Run your for-loop. Here is a while loop that counts from 5 to 10. Each of the three parts of a for loop declaration is optional (initialization, condition, and change), but the semicolons are not optional. The 3 parts are separated by semicolons ( ). Three Parts of a For Loop ¶Ī for-loop combines all 3 parts of writing a loop in one line to initialize, test, and change the loop control variable. In fact, almost every programming language has a for or repeat loop.įigure 1: Comparing App Inventor and Java for loops ¶ 4.2.1. If you have used a language like Scratch or Snap!, you may remember the repeat(n) block where you type in a number of times you want the code to be repeated, just like the AP pseudocode REPEAT block. If you took AP CSP with a block programming language like App Inventor, you probably used a for loop block like below that looks very similar to Java for loops. It is often a simple counter-controlled loop to do the loop body a set number of times. This is usually used when you know how many times you want the loop to execute. Another type of loop in Java is a for loop.
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