Linked List implementation in Visual Basic

Category:

Lists, Collections and Arrays

Type:

Snippets

Difficulty:

Intermediate

Author:

Anonymous

Version Compatibility: Visual Basic 6, Visual Basic 5

More information:

Since Linked list implementation requires pointer and unfortunately VB don't have any. I implement it by making a data type that has element and "Pointer".this so-called "pointer" acts like a pointer but naturally it is more of an Index. [element|n = 0 ] --> [element|n+1]-->[element|n+2] --> and so on... ( --- feel free to give ur corrections or suggestions --- )

Instructions: Copy the declarations and code below and paste directly into your VB project.

Declarations:
Option Explicit Private Type LinkedlistNode element As Integer pointer As Integer End Type Dim length As Integer Dim node As LinkedlistNode

Code:

Function createList(size As Integer)
'creates a List A ;syntax -- A = createList(10)
 length = size
 i% = 0
 
  For i = 0 To i = size
  
      node.element = 0
      node.pointer = i
      i = i + 1
      
  Next
     
End Function

Function setElement(val As Integer, pos As Integer)
'place an element= val to the position = pos
 If (pos > 1) Then
 
   i% = 0
     
   Do Until i = pos
   
       node.pointer = i

Loop
     
       node.element = val
       node.pointer = i
     
     Else
    
        node.element = val
        node.pointer = 0
      
  End If
  
 length = length + 1
  
End Function

Function getElement(pos As Integer) As Integer
'returns the element at the position = pos
 If (pos <= length) Then
   
    For i% = 0 To i = pos
    
      node.pointer = i
      i = i + 1
      
    Next
    
      node.pointer = i
      getElement() = node.element
      
   Else
   
     Err.Raise

End Function

Function setLength(newSize As Integer)
'sets a new size to the List
 If (newSize > length) Then
 
   diff% = newSize - length
   
    For i% = 1 To i = diff
    
      addLast (0)
      i = i + 1
      
    Next
  
  Else
  
    diff = length - newSize
    
    i = 0
    
    Do Until i = newSize
    
      node.pointer = i
      
    Loop
         
      For i = size + 1 To i = length
     
         node.element = Nothing
         node.pointer = Nothing
            
         i = i + 1
         
      Next
      
  End If
  
 length = newSize
         
End Function

Private Function addLast(val As Integer)

addlen% = length + 1
 
  node.element = 0
  node.pointer = addlen
  
End Function