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====== Remove an item from a dictionary ======

<code>using System.Collections.Generic   
using System.Data      
using System.Linq

function Start( ) as void
local oDict as Dictionary<string,int>
local nItem as int
local nItems as int
local aRemove as int[] 
local nLength as int
local oRemove as List<string>
local nChoice as int

nChoice	:= 5		// change to test different possibilities

nItems := 10000	
System.Console.WriteLine( i"Building the dictionary with {nItems} items" )
oDict := Dictionary<string,int>{}
for nItem := 0 upto 10000
  oDict:Add( nItem:ToString(), nItem )
next
System.Console.WriteLine( "Removing items from dictionary" )
aRemove := <int>{ 567, 235, 1, 7435, 8835, 96276, 234, 567 }
oRemove := List<string>{}
foreach nValue as int in aRemove
  System.Console.WriteLine( i"removing {nValue} from dictionary" )
  switch nChoice
    case 1
    // runtime error. A collection cannot be changed during the iteration
      foreach oItem as KeyValuePair<string,int> in oDict
        if oItem:Value == nValue
          oDict:Remove( oItem:Key )
          nLength := oDict:Count
          System.Console.WriteLine( i"removed {nValue} from dictionary, has a remainder length of {nLength}" )
        endif
      next                                                            
    case 2       
    // most primitive working, without LinQ
      foreach oItem as KeyValuePair<string,int> in oDict
        if oItem:Value == nValue
          System.Console.WriteLine( String.Format( "adding key {0} to remove list", oItem:Key ) )
	  oRemove:Add( oItem:Key )
        endif
      next
      foreach cKey as string in oRemove
        oDict:Remove( cKey )
	nLength := oDict:Count
        System.Console.WriteLine( i"removed {cKey} from dictionary, has a remainder length of {nLength}" )
      next
      oRemove:Clear()
    case 3                       
    // runtime error, idea by Robert v.d.Hulst. A collection cannot be changed during the iteration
      var oItems := oDict:Where( {|Item| Item:Value == nValue } )
      foreach var oItem in oItems
        oDict:Remove( oItem:Key )
        System.Console.WriteLine( String.Format( "removed {0} from dictionary, has a remainder length of {1}", oItem:Key, oDict:Count ) )
      next    
    case 4
    // uses LinQ, idea by Robert v.d.Hulst, my personal favorite
      foreach oItem as KeyValuePair<string,int> in oDict:ToList()
        if oItem:Value == nValue
          oDict:Remove( oItem:Key )
          System.Console.WriteLine( String.Format( "removed {0} from dictionary, has a remainder length of {1}", oItem:Key, oDict:Count ) )
        endif
      next     
    case 5
    // uses LinQ - idea from Nick Friend, one liner
      oDict := oDict:Where( {|Item| Item:Value != nValue } ):ToDictionary( {|Item| Item:Key }, {|Item| Item:Value } )
      System.Console.WriteLine( String.Format( "removed entries from dictionary, has a remainder length of {0}", oDict:Count ) )
  end switch
next
	
System.Console.WriteLine("Finished")
return</code>