AP CSP Midterm

Why do we use functions in Karel programs?

-Break down our program into smaller parts -Avoid repeating code -Make our program more readable All of the above

Why does a programmer indent their code?

-Helps show the structure of the code. -Easier for other people to understand. -A key part of good programming style! All of the above

What is the proper format for a single line comment in Karel?

//This is a comment

Say Karel is on a location with one tennis ball. After the following code runs, how many tennis balls will there be at that location?

1

What is printed to the screen when the following program is run? var num = 13 % 3; println(num);

1

What will the following code segment evaluate to? function start(){ var a = 10; var b = 5; var c = 2; var expression = ((a - b) * c) % 3; println(expression); }

1

What will the following program print when run? var numberOne = 5; var numberTwo = 10; if (numberOne == 5) { println(1); } if (numberOne > 5) { println(2); } if (numberTwo < 5) { println(3); } if (numberOne < numberTwo) { println(4); } if (numberOne != numberTwo) { println(5); }

1 4 5

What is the output of the following program? var result = 0; var max = 5; for(var i = 0; i < max; i++){ result += i; } println(result);

10

What will be printed from the following: var x = 4 * 3 + 2 / 5; println(x);

12.4

On the AP exam, the ← operator is used for variable assignment. For example, a ← 10 assigns the value 10 to the variable a. On the AP Exam, the modulus operator is denoted by MOD. The MOD operator has the same precedence as the * and / operators. What will c evaluate to in the following code segment? a ← 18 b ← 4 c ← a MOD b

2

What is the last thing printed by the following program? var start = 30; var stop = 10; for(var i = start; i >= stop; i-=5){ if(i % 2 == 0){ println(i * 2); } else { println(i); } }

20`

On the AP exam, the ← operator is used for variable assignment. For example, a ← 10 assigns the value 10 to the variable a. The value stored in a variable will always be the most recent value assigned. Consider the following code segment. a ← 12 b ← 3 c ← 27 a ← b b ← c c ← a What value is stored in variable c?

3

What is printed to the screen if the user enters '5' when the following program is run? var userNum = readInt("Enter your favorite number: "); var calculatedNum = (userNum * userNum) + userNum; println(calculatedNum);

30

What will be the output of this program? var number = 5; var greater_than_zero = number > 0; if (greater_than_zero){ println(number); }

5

How many total times will Karel move in this program? function start() { move(); for (var i = 0; i < 5; i++) { move(); putBall(); } }

6

What will the following program print when run? for (var j = 0; j < 2; j++) { for (var i = 6; i > 4; i--){ println (i); } }

6 5 6 5

What is wrong with this for loop? for (var i = 0, i < 10, i + 1) { move(); } A. The for loop uses commas instead of semicolons B. It should say i++ instead of i + 1

A and B

The following code continually asks the user for a password until they guess the correct password, then ends. But there is one problem. 1 var SECRET_PASSWORD = "karel"; 2 3 function start(){ 4 while(true){ 5 var password = readLine("Enter your password: "); 6 if(password == SECRET_PASSWORD){ 7 println("You got it!"); 8 } 9 println("Incorrect password, please try again."); 10 } 11 } Which of the following will fix this program?

Add a break; statement after line 7 so that the program doesn't loop infinitely

What will the following program print when run? var above16 = true; var hasPermit = true; var passedTest = false; if (above16 && hasPermit && passedTest){ println("Issue Driver's License"); } else { if (above16 || hasPermit || passedTest) { println("Almost eligible for Driver's License"); } else { println("No requirements met."); } }

Almost eligible for Driver's License

In this code, how many times is the dance function called and how many times is it defined? function start() { move(); dance(); move(); move(); turnLeft(); dance(); dance(); } function dance() { turnLeft(); move(); turnLeft(); turnLeft(); move(); turnLeft(); }

Called 3 times, defined 1 time

How can we teach Karel new commands?

Define a new function

What does the following program do? var radius = readInt("What is the radius of the circle? "); var circle = new Circle(radius); circle.setPosition(radius, radius); add(circle);

Draw a circle on the canvas that always touches the top and left sides of the canvas

What is the output of the following program: (Assume the user enters 'Florence' then 'Fernandez'.) var first_name = readLine("What is your first name? "); var last_name = readLine("What is your last name? "); var whole_name = first_name + last_name; println (whole_name);

FlorenceFernandez

Say you want to write a program to have Karel put down 300 tennis balls. Which control structure would you use?

For loop

What is printed by the following program? var numApples = 10; var numOranges = 5; ' if(numApples < 20 || numOranges == numApples){ println("Hello, we are open!"); } else { println("Sorry, we are closed!"); } println("Sincerely, the grocery store");

Hello, we are open! Sincerely, the grocery store

What is printed by the following program? var isRaining = false; var isCloudy = false; var isSunny = !isRaining && !isCloudy; var isSummer = false; var isWarm = isSunny || isSummer; println("Is it warm: " + isWarm);

Is it warm: false

In the following code, what would be a good Postcondition to write? /* Precondition: Karel is on a spot with a tennis ball facing East * Postcondition: ... */ function getOnTop() { turnLeft(); move(); turnRight(); }

Karel ends one spot above a tennis ball facing East.

What does the mystery function do? function mystery() { while (noBallsPresent()) { move(); } }

Karel moves until it is on a ball

Super Karel starts at Street 1, Avenue 1, facing East in a 5x5 world. What will happen after this code runs? move(); move(); turnRight(); move();

Karel will crash into a wall

Which of the following could be considered a computer?

Smartphone Digital coffee maker Cars All of these choices

If Karel starts at Street 1 and Avenue 1, facing East, where will Karel be, and what direction will Karel be facing after running the following code? (Assume the world is 10x10 in size) move(); turnLeft(); putBall(); turnLeft(); turnLeft(); turnLeft(); move(); turnLeft();

Street 1, Avenue 3, Facing North

Karel starts at Street 1 and Avenue 1, facing East. After calling the stairStep function twice, where will Karel be and what direction will Karel be facing? (assume this is a SuperKarel program and the world is 10x10 in size) function stairStep() { move(); turnLeft(); move(); turnRight(); }

Street 3, Avenue 3, Facing East

What's wrong with this code? function start() { move(); go(); go(); } function go() { move(); move(); } function go() { move(); move(); }

The go function has been defined twice

What makes the following command an invalid Karel command? turnleft();

The l should be a capital L

In the following code: var size = 20; var x = 100; var y = 200; var ball = new Circle(size); ball.setPosition(x, y); What is the meaning of the x variable?

The x coordinate of the center of the circle

What does the following code snippet do? Choose the best answer. function start(){ mouseClickMethod(drawCircle); } function drawCircle(e){ var circle = new Circle(35); circle.setPosition(e.getX(), e.getY()); add(circle); }

This code snippet places a black circle on the screen with a radius of 35 in every place that the mouse is clicked.

Karel starts at Street 1, Avenue 1, facing East in a 5x5 world. What will happen after this code runs? move(); putball(); move(); move(); move(); move(); move();

This code won't run because of a syntax error

In the following code below from the Cleanup Karel example, what is the purpose of If Statement #2? // This program has Karel walk down the // row and clean up all of the tennis balls // on the way. function start() { while (frontIsClear()) { // If statement #1 if (ballsPresent()) { takeBall(); } move(); } // If statement #2 if (ballsPresent()) { takeBall(); } }

To pick up the ball that is in the last spot, if there is one

What is the purpose of using a for loop in code?

To repeat something a fixed number of times

What is top down design?

Top down design is a way of designing your program by starting with the biggest problem and breaking it down into smaller and smaller pieces that are easier to solve.

How can we improve the following program? function start() { move(); move(); move(); move(); move(); move(); move(); move(); move(); }

Use a for loop to repeat the move command

What will be the output when the following code runs? function start(){ var loggedIn = false; println("User logged in?: " + !loggedIn); }

User logged in?: true

The following program should draw a circle on the screen 1 function start(){ 2 var circle = new Circle(40); 3 circle.setPosition(getWidth() / 2, getHeight() / 2); 4 circle.setColor(Color.blue); 5 } But when we run this code, we don't see the circle. What is missing from our start function?

We create the circle and position it correctly on the screen, but we never add it to the screen. We need to add the line add(circle); after line 4

On the AP exam, INPUT() is used to accept a value from the user and DISPLAY() is used to display a value. Values that are displayed are NOT started on a new line, but do contain a space afterwards. Consider the code segment below. DISPLAY ("What is your name?") name ← INPUT () DISPLAY ("Hello") DISPLAY (name) What is displayed as a result if the user inputs "Rowan", then enter into the program?

What is your name? Rowan Hello Rowan

What condition should be used in this while loop to get Karel to pick up all the tennis balls on the current location? while (________) { takeBall(); }

ballsPresent()

Choose the best response: A function passed to an event handler that is called every time a certain event happens is called a

callback function.

What is the value of the boolean variable canVote at the end of this program? var age = 17; var isCitizen = true; var canVote = age >= 18 && isCitizen;

false

We want to print the phrase "CodeHS is the best" exactly 25 times. What kind of control structure should we use?

for loop

Which of the following is the correct way to define a turnRight function in Karel?

function turnRight() { turnLeft(); turnLeft(); turnLeft(); }

What are the coordinates of the center of the window?

getWidth() / 2, getHeight() / 2

In a graphics canvas, what are the coordinates of the bottom right corner of the window?

getWidth(), getHeight()

Suppose we've written a function drawSquare that we want to call every time the mouse is clicked. How can we do this?

mouseClickMethod(drawSquare);

Which of the following commands is a valid Karel command?

move();

Which of the following lines of code would be conssidered the highest level of code?

move();

What will be the output of this program? var number = 5; var greater_than_zero = number > 0; if (greater_than_zero){ if (number > 5) { println(number); } }

nothing will print`

If you were given the following variables: var distance = 2; var time = 30; What line of code would print the speed in km/hr if the distance is given in km and the time is given in minutes? (Speed = distance/time)

println(distance/(time/60));

How many times will the following program print "hello"? var i = 0; while(i < 10){ println("hello"); }

this code will loop infinitely

Which of the following is not a valid condition to go in an if statement for Karel?

turnLeft()

Which of the following choices is a properly formed JavaScript variable name, meaning it is both legal in the JavaScript language and considered good style?

userAge

You want to read input from the user to know how many apples they would like to buy. Which statement should you use to read in a number from the user?

var applesToBuy = readInt("How many apples would you like? ");

If a user enters a diameter value in the variable diameter, how would we use this to draw the correct sized circle?

var circle = new Circle(diameter/2); circle.setPosition(100,100); add(circle);

You are splitting up all of your apples equally between 3 people. Which statement below will calculate how many apples will be left over?

var leftOver = numApples % 3;

A store has 20 apples in its inventory. How can you store this information in a JavaScript variable?

var numApples = 20;

If you wanted to use the following code to draw a circle to the canvas with the radius, and x and y coordinates given by the user, how would you ask for this information? var circle = new Circle(radius); circle.setPosition(x, y); circle.setColor(color); add(circle);

var x = readInt("What is the x coordinate? ");var y = readInt("What is the y coordinate? ");var radius = readInt("What is the radius of the circle? ");

We want to simulate constantly flipping a coin until we get 3 heads in a row. What kind of loop should we use?

while loop