CS 1 - Functions

Why do we write functions?

• Make our code easier to understand by giving a readable name to a group of instructions

• Avoid writing repeated code

• Make our code reusable

• All of the above

In the following function printThreeTimes:

function printThreeTimes(word){

println(word);

println(word);

println(word); }

What is the parameter of the function?

• printThreeTimes

• function

• println

• word

What is printed by the following program?

function printNumbers(two, one, zero){

println(two);

println(one);

println(zero);

}

function start(){

var zero = 0;

var one = 1;

var two = 2;

printNumbers(zero, one, two);

}

• 2, 1, 0

• 0, 1, 2

• zero, one, two

• two, one, zero

How many parameters go into the function sum, and how many return values come out of the function sum?

function sum(first, second, third){

var result = first + second + third;

println(first);

println(second);

println(third);

return result;

}

• 3 parameters go in, 1 return value comes out

• 3 parameters go in, 3 return values come out

• 1 parameter goes in, 4 return values come out

• 1 parameter goes in, 1 return value comes out

“It’s a bird! It’s a plane! No, it’s Superman!”We want to write a function isSuperman that takes in two parameters isBird and isPlane and returns true if it is in fact Superman, and false otherwise.If it’s not a bird and it’s not a plane, it must be Superman.Which of the following functions is the correct implementation of isSuperman?

• function isSuperman(isBird, isPlane){ return isBird || isPlane; }

• function isSuperman(isBird, isPlane){ return isBird && isPlane; }

• function isSuperman(isBird, isPlane){ return !isBird || !isPlane; }

• function isSuperman(isBird, isPlane){ return !isBird && !isPlane; }

In the following code:

function start(){ var length = 5; var width = 4; rectangleArea(length, width); } // This function prints out the area of // a triangle given its base and height function rectangleArea(base, height){ var area = base * height; println(area); }

What are the names of the parameters?

• length and width

• base and width

• length and base

• base and height

In the following code:

function drawCircle(radius, x, y, color) { var circle = new Circle(radius); circle.setPosition(x, y); circle.setColor(color); add(circle); }

What is the minimum number of parameters that must be given when calling the ‘drawCircle’ function?

• 1

• 2

• 3

• 4

What will be printed to the screen when the following program is run?

function start(){ println(doubleNumber(doubleNumber(10))); } function doubleNumber(x){ var doubledX = 2 * x; return doubledX; }

• 80

• 40

• 20

• 10

Which of the following is NOT a use of the function drawCircle in the following program?

var RADIUS = 35;

function start() {

var centerX = getWidth() / 2;

var centerY = getHeight() / 2;

drawCircle(RADIUS, Color.red, centerX, centerY);

}

function drawCircle(radius, color, x, y) {

var circle = new Circle(radius);

circle.setColor(color);

circle.setPosition(x, y);

add(circle);

}

• Draw circles in various positions on the canvas

• Draw circles with various colors on the canvas

• Draw different shapes on the canvas

• Draw circles with various sizes on the canvas