Cross Ref > Data Structures

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.

[Not specified yet. Coming...]

Access VBA:   x = Array() Arrays in Access VBA 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

Languages Focus

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

Perl:   % Array Preface Syntax Example: my %weekdays = ( 'Sun' => 'Sunday', 'Mon' => 'Monday', 'Tue' => 'Tuesday', 'Wed' => 'Wednesday', 'Thu' => 'Thursday', 'Fri' => 'Friday', 'Sat' => 'Saturday', ); my $day_of_the_week = $weekdays{'Mon'};  Perl Associative Array (% Array Preface)	Access VBA:   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"))  Access VBA Associative Array (Collection)

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).

Perl:  Perl supports both pointers and references.	Access VBA:   Not Supported Same as VB Classic. Access VBA does not offer developer defined pointers.