Question

This is a follow up question to a previous question I asked about calculating a straight hand..not exactly the same…This is the method to read in cards- it works- but is there a better way- to do this using console input in C …

void read_cards(int num_in_rank[], int num_in_suit[])
{
  bool card_exists[NUM_RANKS][NUM_SUITS];
  char ch, rank_ch, suit_ch;
  int rank, suit;
  bool bad_card;
  int cards_read = 0;

  for (rank = 0; rank < NUM_RANKS; rank++) {
    num_in_rank[rank] = 0;
    for (suit = 0; suit < NUM_SUITS; suit++)
      card_exists[rank][suit] = false;
  }

  for (suit = 0; suit < NUM_SUITS; suit++)
    num_in_suit[suit] = 0;

  while (cards_read < NUM_CARDS) {
    bad_card = false;

    printf("Enter a card: ");

    rank_ch = getchar();
    switch (rank_ch) {
      case '0':           exit(EXIT_SUCCESS);
      case '2':           rank = 0; break;
      case '3':           rank = 1; break;
      case '4':           rank = 2; break;
      case '5':           rank = 3; break;
      case '6':           rank = 4; break;
      case '7':           rank = 5; break;
      case '8':           rank = 6; break;
      case '9':           rank = 7; break;
      case 't': case 'T': rank = 8; break;
      case 'j': case 'J': rank = 9; break;
      case 'q': case 'Q': rank = 10; break;
      case 'k': case 'K': rank = 11; break;
      case 'a': case 'A': rank = 12; break;
      default:            bad_card = true;
    }

    suit_ch = getchar();
    switch (suit_ch) {
      case 'c': case 'C': suit = 0; break;
      case 'd': case 'D': suit = 1; break;
      case 'h': case 'H': suit = 2; break;
      case 's': case 'S': suit = 3; break;
      default:            bad_card = true;
    }

    while ((ch = getchar()) != '\n')
      if (ch != ' ') bad_card = true;

    if (bad_card)
      printf("Bad card; ignored.\n");
    else if (card_exists[rank][suit])
      printf("Duplicate card; ignored.\n");
    else {
      num_in_rank[rank]++;
      num_in_suit[suit]++;
      card_exists[rank][suit] = true;
      cards_read++;
    }
  }
}

I know the case statement can have a few optimizations-i.e. using toupper; better representation the card values, etc..Suggestions- please. The code is reflective of C99…

Answer 1

The code looks fine to me. It’s actually quite well-done and readable in my opinion.

It seems like you’re asking about optimizations – don’t worry about optimizing until you’re sure that you need it, otherwise it just makes your code less legible and more prone to bugs. In particular, this function is going to spend well over 99.99% of the time it is running just waiting for the user to type, so there is no need to optimize it.

I don’t think it’s necessarily bad to use fall-through to capture both upper and lowercase input in a switch statement, especially with as few cases as you have. It’s just a little more typing.

If there’s actually an issue with this code and it’s not compiling or not doing what it’s supposed to, please describe the problem.

Edit: The only thing you might want to change is to get rid of the explicit cases for ranks 0-9, and instead combine them all into one fall through case with the body:

rank = rank_ch - '0';

That’s a relatively common C idiom for converting a number stored as a character to an integer, so it should be legible to other programmers who read it.