Karel the Robot – Quick-Start User Guide

1. What Is Karel?

Karel lives in a 2-D grid (“world”) of square cells. He can face North/East/South/West, move one cell at a time, pick up or put down “beepers,” and detect walls.

2. Simulator Interface

Code Editor: Write your program here.
Compile & Run: Lex, parse, and execute step-by-step.
Stop: Immediately halt execution (for infinite loops).
Console: Logs moves, errors, and debug messages.
Upload Map: Load a .txt or .kw world file.
Map View: ASCII display of walls (red), beepers, and Karel (green).
Manual Editor: Draw your own world, then import it.

3. Syntax Essentials

Every statement ends with a semicolon ;.
Every command or condition must have parentheses ().
Use if (…){…} [else{…}] and while (…){…}.
Comments begin with //.

4. Built-in Commands

Movement

Command	Effect
`move()`	Step forward if no wall ahead.
`turnLeft()`	Rotate 90° counter-clockwise.

Beeper Handling

Command	Effect
`pickBeeper()`	Pick one beeper from current cell.
`putBeeper()`	Place one beeper into current cell.

Sensors & Conditions

Condition	True When…
`frontIsClear()`	No wall immediately in front.
`frontIsBlocked()`	Wall immediately in front.
`leftIsClear()`	No wall on Karel’s left.
`leftIsBlocked()`	Wall on Karel’s left.
`rightIsClear()`	No wall on Karel’s right.
`rightIsBlocked()`	Wall on Karel’s right.
`nextToABeeper()`	One or more beepers in this cell.
`notNextToABeeper()`	No beepers in this cell.
`facingNorth()`, `facingEast()`, …	Karel’s orientation matches the named direction.
`anyBeepersInBeeperBag()`	Bag contains ≥ 1 beeper.
`noBeepersInBeeperBag()`	Bag is empty.

5. Example

while ( notNextToABeeper() ) {
  move();
}
pickBeeper();
turnLeft();
move();
putBeeper();

6. Tips

Sketch Karel’s path on graph paper first.
Always check frontIsClear() before move().
Use the Stop button to escape accidental infinite loops.
Combine if and while for complex behaviors.

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