Nice use for the conditonal operaror

This is a discussion on Nice use for the conditonal operaror within the C Programming forums, part of the General Programming Boards category; Hi I came across a nice use for conditional operator. I always hated dealing text for "You have 1 units" ...

  1. #1
    Registered User hamsteroid's Avatar
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    Nice use for the conditonal operaror

    Hi I came across a nice use for conditional operator. I always hated dealing text for "You have 1 units" or "You have 2 units" - ie, dealing with plural for single items.

    Code:
    int main(void)
    {
      const double unit_price = 3.50;   /* unit price in euro */
      const double discount1 = 0.05;    /* discount for more than 10 */
      const double discount2 = 0.10;    /* discount for more than 20 */
      const double discount3 = 0.15;    /* discount for more than 50 */
      double total_price = 0.0;
      int quantity = 0;
    
      printf("\nWelcome to the shop. Basic unit costs %.2f. Discounts available.",unit_price);
      printf("\n5%% off on more than 10. 10%% off on more than 20. 15%% off on more than 50!");
      printf("\nEnter the number of units you want to buy: ");
      scanf("%d",&quantity);
    
      total_price = quantity*unit_price*(1.0 -
                      (quantity>50 ? discount3 : (
                         quantity>20 ? discount2 : (
                           quantity>10 ? discount1 : 0.0))));
    
      printf("The price for %d unit%s is %.2f euro.\n", quantity, quantity>1 ? "s" : "", total_price);
      /* quantity>1 check shows how to deal single or plural units */
      return 0;
    }
    The code segment:
    Code:
    quantity, quantity>1 ? "s" : ""
    is pretty cool. It's one in my bookmarks. I love that! Going back I always neglected the shorthand conditional op.

    Welcome to the shop. Basic unit costs 3.50. Discounts available.
    5% off on more than 10. 10% off on more than 20. 15% off on more than 50!
    Enter the number of units you want to buy: 1
    The price for 1 unit is 3.50 euro.
    Last edited by hamsteroid; 04-01-2007 at 03:39 AM. Reason: showing the output part.

  2. #2
    CSharpener vart's Avatar
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    in printf it increases readability...
    but in total_price calculations - I prefer if/else for readability...
    Code:
    coeff = 1.0;
    if(quantity>50 ) coeff -= discount3 ;
    else if (quantity>20 ) coeff -= discount2;
    else if (quantity>10 ) coeff -= discount1;
    
    total_price = quantity*unit_price*coeff;
    for me is a lot more easier to understand than the original code
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

  3. #3
    Registered User hamsteroid's Avatar
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    Actually I agree with you vart. Though I do like the single/plural trick.

    Code:
    quantity>1 ? "s" : ""
    The nested discount example above in the main code reminds me of that cursed nested DECODE statement in PLSQL where I come across it a lot - it's usually subnested to the high heavens!

    The simple plural example at the end is nice though I must admit.

  4. #4
    Gawking at stupidity
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    Keep in mind that 0 should also be plural, but your check is for >1. 1 is the only case in which it is not plural.

    0 dollars
    1 dollar
    2 dollars
    If you understand what you're doing, you're not learning anything.

  5. #5
    and the hat of wrongness Salem's Avatar
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    Also bear in mind, that if you come to translate this code into other languages, a simple search for all strings isn't going to work so well.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  6. #6
    Registered User hamsteroid's Avatar
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    Quote Originally Posted by Salem View Post
    Also bear in mind, that if you come to translate this code into other languages, a simple search for all strings isn't going to work so well.
    That is problem is close to heart sometimes, I'm dealing with 2-3 byte Kanji characters in some rather sticky invoices of late

  7. #7
    Registered User hamsteroid's Avatar
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    Quote Originally Posted by itsme86 View Post
    Keep in mind that 0 should also be plural, but your check is for >1. 1 is the only case in which it is not plural.

    0 dollars
    1 dollar
    2 dollars
    Thanks! I want to hire you as my code tester!

  8. #8
    CSharpener vart's Avatar
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    as well as 21 dollar should be singular
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

  9. #9
    Registered User hamsteroid's Avatar
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    euros vs euro..... in Euroland - most folk say "5 euro" and a few say "5 euros". All I notice is that I get less for my euro!

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