Short Stack | CodeHS

4: Short Stack

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Functions

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1 point

Write a program to have Karel create a short stack of tennis balls.

Karel should move one spot, put down two tennis balls, and then move again.

Ending World

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Karel's Built in Commands

Commands

`move();` JavaScript		`turnLeft();` JavaScript
`putBall();` JavaScript		`takeBall();` JavaScript

Functions

Writing a Function

Writing a function is like teaching karel a new word.

Naming Functions: You can name your functions whatever you want, but you can't have spaces in the function name.

Remember that each open bracket { must match with a close bracket }

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

function turnAround() {
    turnLeft();
    turnLeft();
}

function yourFunctionName() {
  // Code that will run when you make a call to
  // this function.
}JavaScript

Conditional Statements

If Statements

Remember that each open bracket { must match with a close bracket }

if (condition) {
  // code that will run if the condition is true
}JavaScript

if (condition) {
  // code that will run if the condition is true
} else {
  // code that will run if condition is not true
}JavaScript

Example of if statements

if (frontIsClear()) {
    move();
}

if (ballsPresent()) {
    takeBall();
} else {
    move();
}JavaScript

Karel Conditions

Don't forget the () at the end

frontIsClear()
leftIsClear()
rightIsClear()

facingNorth()
facingSouth()
facingEast()
facingWest()

ballsPresent()
            JavaScript

frontIsBlocked()
leftIsBlocked()
rightIsBlocked()

notFacingNorth()
notFacingSouth()
notFacingEast()
notFacingWest()

noBallsPresent()
            JavaScript

Loops

Remember that each open bracket { must match with a close bracket }

While Loops

while (CONDITION) {
  // Code that will run while the CONDITION is true.
  // Once the CONDITION is no longer true,
  // it will stop.
}JavaScript

Example of while loops

/* This moves Karel to a wall */
while (frontIsClear()) {
    move();
}JavaScript

For Loops

Note: you can use both "let" and "var" in your for loops (they are two types of JavaScript variables). Use whichever you have been taught in your course.

for (let i = 0; i < COUNT; i++) {
  // Code that will run 'COUNT' times
}

// Can also use "var" to define the "i" (depends on your course)
for (var i = 0; i < COUNT; i++) {
  // Code that will run 'COUNT' times
}JavaScript

Example of for loops

/* This puts down 10 balls */
for (let i = 0; i < 10; i++) {
    putBall();
}

// Or, if your course teaches "var":
for (var i = 0; i < 10; i++) {
    putBall();
}JavaScript

You can have multiple statements or function calls in a for loop.

/* This puts down five balls and moves after each one */
for (let i = 0; i < 5; i++) {
    putBall();
    move();
}

// Or, if your course teaches "var":
for (var i = 0; i < 5; i++) {
    putBall();
    move();
}JavaScript

Use for-loops when you want to repeat something a fixed number of times.

Use while-loops when you want to repeat something as long as a condition is true.

Comments

/* A multi-line comment describes your code
 * to someone who is reading it. */

// Use single line comments to clarify code.JavaScript

Starting World

Ending World

Autograder Results

Your Output

Solution Output

Errors:

Grader Results

Errors:

Ending World

Karel's Built in Commands

Commands

Functions

Writing a Function

Conditional Statements

If Statements

Example of if statements

Karel Conditions

Loops

While Loops

Example of while loops

For Loops

Example of for loops

Comments

Comments

Products

Computer Science Curriculum

Customizable K-12 Computer Science Curriculum

Error: Line -1

Autograder Results

Your Output

Solution Output

Errors:

Grader Results

Errors:

Ending World

Karel's Built in Commands

Commands

Functions

Writing a Function

Conditional Statements

If Statements

Example of if statements

Karel Conditions

Loops

While Loops

Example of while loops

For Loops

Example of for loops

Comments

Comments