IT SOLUTIONS
Your full service technology partner! 
-Collapse +Expand
To/From Code
-Collapse +Expand Cross Ref Guide
-Collapse +Expand Members-Only
Sign in to see member-only pages.
   ► KBTo/From GuidesVB ClassicData Structures  Print This     

Cross Ref > Data Structures

By Mike Prestwood

VB Classic versus C++/CLI: A side by side comparison between VB Classic and C++/CLI.

 
Data Structures
 

Data structures allow you to store and work with data. Common data structures include arrays, associative arrays, etc.

Array

[Other Languages] 

Languages Focus

A data structure in which individual values (called elements or items) may be located by reference to one or more integer index variables, the number of such indices being the number of dimensions in the array.

Arrays can start with an index value of 0 or 1, sometimes referred to as 0 based or 1 based.

VB Classic:   x = Array()

Arrays in VB Classic use a 0-based indice. Use UBound to get the number of elements. UBound returns -1 if the array has no elements, 0 if it has 1, 1 if it has 2, etc.

Syntax Example:  
Dim MyArray As Variant
Dim i As Integer
 
MyArray = Array("Mike", "Lisa", "Felicia", "Nathan")
 
If UBound(MyArray) > -1 Then
  For i = 0 To UBound(MyArray)
    MsgBox (MyArray(i))
  Next
End If
[Not specified yet. Coming...]




Associative Array

[Other Languages] 
A set of unique keys linked to a set of values. Each unique key is associated with a value. Think of it as a two column table. MyArray['CA'] = 'California' MyArray['AR'] = 'Arizona'

Languages Focus

Associative arrays are also known as a dictionary or a hash table in other languages.

VB Classic:   Collection

In addition to Add and Item, collections also offer Count and Remove. Notice that Add uses the format of Value, Key (which is backwards from many other languages).

Syntax Example:
Dim States As New Collection
   
States.Add "California", "CA"
States.Add "Nevada", "NV"
    
MsgBox (States.Item("CA"))
[Not specified yet. Coming...]




Pointers

[Other Languages] 

General Info: Pointers / References

A pointer is a variable type that allows you to refer indirectly to another object. Instead of holding data, a pointer holds the address to data -- the address of another variable or object. You can change the address value a pointer points to thus changing the variable or object the pointer is pointing to.

A reference is a type of pointer that cannot change and it must always point to a valid storage (no nulls).

VB Classic:   Not Supported

VB6 does not officially offer developer defined pointers. However, VB5 and VB6 does have unsupported and undocumented VarPtr, StrPtr, and ObjPtr types but you probably should avoid them.

[Not specified yet. Coming...]




Go ahead!   Use Us! Call: 916-726-5675  Or visit our new sales site: 
www.prestwood.com


©1995-2024 Prestwood IT Solutions.   [Security & Privacy]