freeCodeCamp/guide/english/certifications/javascript-algorithms-and-data-structures/basic-javascript/counting-cards/index.md

title

title
Counting Cards

Counting Cards

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Hints

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.

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Solutions

Solution 1 (Click to Show/Hide)

function cc(card) {
  // Only change code below this line
  switch (card) {
    case 2:
    case 3:
    case 4:
    case 5:
    case 6:
      count++;
      break;
    case 10:
    case "J":
    case "Q":
    case "K":
    case "A":
      count--;
      break;
  }
  if (count > 0) {
    return count + " Bet";
  } else {
    return count + " Hold";
  }
  // Only change code above this line
}

Code Explanation

• Check 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'.
• Check the value of count and return the appropriate response.

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, the if statement checks count, which is now 0.
• This then drops down to the else statement, which will return 0 Hold.

Note: As mentioned earlier, the switch statement could have also been an else if statement.

Solution 2 (Click to Show/Hide)

function cc(card) {
  // Only change code below this line
  var regex = /[JQKA]/;
  if (card > 1 && card < 7) {
    count++;
  } else if (card === 10 || String(card).match(regex)) {
    count--;
  }

  if (count > 0) return count + " Bet";
  return count + " Hold";

  // Only change code above this line
}

Code Explanation

· The function first evaluates if the condition card is a value greater than 1 and lower than 7, in which case it increments count by one. · Then if the card is 10 or higher it decrements count by one. · The variable regex is a regular expression representing values (letters) for the higher cards. · The else statement checks those values with the || (logical OR) operator; first for 10 and then for any string that matches the regular expression using String.match().

Relevant Links

• Card counting at Wikipedia
• Challenge: Selecting from many options with Switch Statements
• Challenge: Chaining If Else Statements
• Challenge: Increment a Number with JavaScript