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3042 :: [noob] enums and index

• DTxplorer (orginal) [2017-07-12T13:24:02+02:00] view original

  Sorry for the noobish question. I want to understand how using the enums like in C/C++

  // Example program
  #include <iostream>
  #include <string>
  using namespace std;
  
  int main()
  {
      enum country {ITALY, GERMANY, PORTUGAL};
      string capital[] = {"Rome", "Berlin", "Lisbon"};
      cout<<capital[ITALY];
  }
  Run

  prints "Rome" as expected

  type country = enum
    ITALY=int(0),
    GERMANY=int(1),
    PORTUGAL=int(2)
  
  var capital:array = ["Rome", "Berlin", "Lisbon"]
  
  echo capital[ITALY] # error, "ITALY" is not equal to 0 !
  Run

  The debugger prints a type mismatch. The only solution is to call ord() function but the enum as declared as integers. Thank you in advance for your indulgence.

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• Araq (orginal) [2017-07-12T13:38:53+02:00] view original

  No, arrays can use enums as the index type (and I use this feature all the time):

  type country = enum
    ITALY,
    GERMANY,
    PORTUGAL
  
  var capital: array[country, string] = ["Rome", "Berlin", "Lisbon"]
  
  echo capital[ITALY]
  Run

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• Krux02 (orginal) [2017-07-12T14:08:48+02:00] view original

  I did not know this is possible. Seems very interesting.

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• DTxplorer (orginal) [2017-07-12T19:07:34+02:00] view original

  Thanks for the help Araq.

  The Nim enum behaves differently so I think this code reproduces better the Cpp code behaviour.

  # I wonder if it's a good practise
  const
    ITALY = 0
    GERMANY = 1
    PORTUGAL = 2
  
  var capital: array = ["Rome", "Berlin", "Lisbon"]
  
  echo capital[PORTUGAL]
  Run

  Sorry for these snippets full of unused variables ;)

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• LeuGim (orginal) [2017-07-12T19:22:36+02:00] view original

  If you'll add a type cast in inddexing, your snippet will work (either of them):

  echo capital[ITALY.int]
  Run

  And Byou can omit type in variable declaration altogether:

  var capital = ["Rome", "Berlin", "Lisbon"]
  Run

  But if the point is to just use explicit values for enum items, then you can add them to Araq's snippet. Then you don't need type casts using the variable.

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