Lesson Review Counting Cards

Checkpoint: Counting Cards

About Blackjack

In the casino game Blackjack, a player can gain an advantage over the house by keeping track of the relative number of high and low cards remaining in the deck. This is called Card Counting.

Having more high cards remaining in the deck favors the player. Each card is assigned a value according to the table below. When the count is positive, the player should bet high. When the count is zero or negative, the player should bet low.

Value	Cards
+1	2, 3, 4, 5, 6
0	7, 8, 9
-1	10, 'J', 'Q', 'K','A'

Instructions

You will write a card counting function. It will receive a card parameter and increment or decrement the global count variable according to the card's value (see table). The function will then return the current count and the string "Bet" if the count is positive, or "Hold" if the count is zero or negative.

Example Output:

• -3 Hold
• 5 Bet

Remember to use Read-Search-Ask if you get stuck. Try to pair program. Write your own code.

Useful Links

• Waypoint: Selecting from many options with Switch Statements
• Waypoint: Chaining If Else Statements
• Waypoint: Increment a Number with Javascript

Problem Explanation:

• Change the code below // Only change code below this line and up to // Only change code above this line
• Take note that you are editing the inside of the cc function
• Use what you've learned to check the value of each card parameter passed into the function
• Keep a running count of that number
• If the final count is 1 or greater, return # Hold
• If the final count is 0 or less, return # Bet

Hint: 1

• Use a switch (or else if) statement to count the value of each card.

Hint: 2

• Add/subtract the value of each card to variable count. If the card is worth 0, don't do anything!

Hint: 3

• After you've counted the cards, use an if statement to check the value of count. Also, make sure your return has a space between the number and the string. If you are familiar with Ternary Operatiosn then you can use that.

Spoiler Alert!

Solution ahead!

Code Solution:

var count = 0;

function cc(card) {
  // Only change code below this line
  switch (card){
    case 2:
    case 3:
    case 4:
    case 5:
    case 6:
      count+=1;
      break;
    case 7:
    case 8:
    case 9:
      count+=0;
      break;
    case 10:
    case 'J':
    case 'Q':
    case 'K':
    case 'A':
      count-= 1;
      break;
  }

  return count + (count > 0 ? " Bet" : " Hold");
  // Only change code above this line
}

// Add/remove calls to test your function.
// Note: Only the last will display
cc(2); cc(3); cc(7); cc('K'); cc('A');

Code Explanation:

• Checks the value of each card via a switch statement
• The variable count:
  • Increases by 1 if the card is a 2, 3, 4, 5, or 6
  • Since 7, 8, and 9 aren't worth anything, we ignore those cards in our switch statement.
  • Decreases by 1 if the card is a 10, 'J', 'Q', 'K', or 'A'
• Returns count and concatenate Bet or Hold depending on the value of count using a ternary operator.

Example Run

• cc(2); runs
• The switch statement hits case 2, jumps down and adds 1 to the variable count
• The switch statement then hits the break and cc(3); runs
• This cycle continues until the final call is made, cc('A');
• After the switch statement, we return the value of count which is 0
• We also have on the same return statement a ternary operator which concatenate the right string based on the value of count, which will return 0 Hold

Note You could also use an if - else statement to return the right information.

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