Thread: Can i have a generic indexer this[TKey key] property? it requiers only int why?

  1. #1
    Registered User
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    Nov 2017
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    Can i have a generic indexer this[TKey key] property? it requiers only int why?

    Code:
     public class MyDictionary<TKey, TValue> : MyIDictionary<TKey, TValue>
        {
            private object[] _items;
            //private int index = 0;
            public MyDictionary()
            {
                _items = new object[10];
            }
    
    
            public TValue this[TKey key]
            {
                get
                {
                    return (TValue)_items[key];//cannot implicitly convert type 'TKey' to 'int'
                }
                set
                {
                    _items[key] = value;
                }
            }

  2. #2
    Lurking whiteflags's Avatar
    Join Date
    Apr 2006
    Location
    United States
    Posts
    9,533
    You can do it, but where you went wrong is that an array of objects expects the index to be an int. You have to search the array _items yourself and return the right object.

    Maybe something like this is a good start.
    Code:
    public class MyDictionary<TKey, TValue> : MyIDictionary<TKey, TValue>
    {
       private KeyValuePair<TKey, TValue>[] _items;
       private int index = 0;
       public MyDictionary()
       {
           _items = new KeyValuePair<TKey, TValue>[10];
       }
    
    
       public TValue this[TKey key]
       {
           get
           {
               foreach (KeyValuePair<TKey, TValue> kvp in _items)
               {
                      if (key.Equals(kvp.Key))
                         return kvp.Value;
               }
               throw new System.ArgumentOutOfRangeException(key.ToString(), "not in dictionary");
           }
           set
           {
               _items[index] = new KeyValuePair<TKey, TValue>(key, value);
               ++index;
           }
       }
    }
    Nothing was tested.
    Last edited by whiteflags; 3 Weeks Ago at 03:04 AM.

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