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collections [2018/02/04 19:42]
wolfgangriedmann
collections [2018/02/05 06:20] (current)
wolfgangriedmann
Line 20: Line 20:
   * [[https://​docs.microsoft.com/​en-us/​dotnet/​standard/​collections/​commonly-used-collection-types|MSDN:​ Commonly used collection types]]   * [[https://​docs.microsoft.com/​en-us/​dotnet/​standard/​collections/​commonly-used-collection-types|MSDN:​ Commonly used collection types]]
  
-But it is very important ​to know that you **cannot** change a collection while you are using it in a ''​foreach''​ loop.+There are a few very important ​things you should ​know about collections:​ 
 +  * They are not arrays, and therefore they are **0-based**,​ so the first member of the collection is **element 0**, and there is no compiler switch ​that can change this, because it are the classes itself that are written this was 
 +  * You **cannot** change a collection while you are using it in a ''​foreach''​ loop. 
 +  * most collections are using generics, to you need to specify the type(s) of the elements in the declaration of the variable 
 + 
 +A few code samples (please look at samples for the single classes [[collections:​list|System.Collections.Generic.List]] and [[collections:​dictionary|System.Collections.Generic.Dictionary]]) for deeper looks): 
 +<​code>​using System.Collections.Generic 
 +local oList as List<​string>​ 
 +local nCount as int 
 + 
 +oList := List<​string>​{} 
 +oList:Add( "Hi girls" ) 
 +oList:Add( "Hi guys" ) 
 +nCount := oList:​Count ​                  
 +foreach cItem as string in oList 
 +  // do something 
 +next 
 +oList:​Remove( "Hi guys" ) 
 +oList:​RemoveAt( 0 )</​code>​ 
 +<​code>​local oDictionary as Dictionary<​int,​string>​ 
 +local nCount as int 
 + 
 +oDictionary := Dictionary<​int,​string>​{} 
 +oDictionary:​Add( 1, "Hi girls" ) 
 +oDictionary:​Add( 2, "Hi guys" ) 
 +foreach oItem as KeyValuePair<​int,​string>​ in oDictionary 
 +  // do something 
 +next</​code>​ 
 + 
 + 
 + 
 + 
  
  
  
  
collections.txt · Last modified: 2018/02/05 06:20 by wolfgangriedmann