Java Map equivalent in C

Question

I m trying to hold a list of items in a collection with a key of my choice  In Java  I would simply use Map as follows   class Test     Map lt Integer String gt  entities     public String getEntity Integer code        return this entities get code           Is there an equivalent way of doing this in C   System Collections Generic Hashset doesn t uses hash and I cannot define a custom type key System Collections Hashtable isn t a generic class System Collections Generic Dictionary doesn t have a get Key  method

User · Answer

class Test       Dictionary lt int  string gt  entities       public string GetEntity int code                   java s get method returns null when the key has no mapping            so we ll do the same          string val          if  entities TryGetValue code  out val               return val          else             return null

User · Answer

You can index Dictionary  you didn t need  get    Dictionary lt string string gt  example   new Dictionary lt string string gt         example Add  hello   world        Console Writeline example  hello       An efficient way to test get values is TryGetValue  thanx to  Earwicker    if  otherExample TryGetValue  key   out value         otherExample  key     value   1      With this method you can fast and exception-less get values  if present    Resources   Dictionary-Keys  Try Get Value

User · Answer

Dictionary lt    is the equivalent   While it doesn t have a Get      method  it does have an indexed property called Item which you can access in C  directly using index notation   class Test     Dictionary lt int String gt  entities     public String getEntity int code        return this entities code           If you want to use a custom key type then you should consider implementing IEquatable lt   and overriding Equals object  and GetHashCode   unless the default  reference or struct  equality is sufficient for determining equality of keys   You should also make your key type immutable to prevent weird things happening if a key is mutated after it has been inserted into a dictionary  e g  because the mutation caused its hash code to change

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