Copyright © 2004-2005
| cArray: Find |
Uses a callback method to search an array for the first element that matches the criteria.
Public Function Find( ByRef Arr As Variant, ByVal AddressOfMatch As Long ) As Variant
The function signature for the callback has a specific format.
Public Function FindCallback(ByRef x As [Array Datatype]) As Boolean
' return True if x matches your criteria.
End Sub
The [Array Datatype] must be replaced with the datatype of the array. If the
array is an array of Variants, then [Array Datatype] would be a Variant, not
any specific sub-type within the variants of the array.
The callback method signature needs to have 1 parameter that is of aByRef definition for the the datatype the same as the array. The callbackfunction must return a Boolean value indicating if the passed-by-refelement matches the criteria of the matching routine.
It is extremely important to define the callback method correctly. Ifthe method is incorrect, the application may crash.
In the examples below, a String array is searched using variouscriteria. The two callback functions (MatchGreetings, MatchNonGreetings) aredefined with 1 parameter of a ByRef String and returns a Boolean. If the array datatype is a Long, the the callback will be defined as aByRef Long.
None of the values should be changed during the search.
Private Sub Main() FindFirstGreeting FindLastGreeting FindAllGreetings FindAllNonGreetingsEnd Sub' Searches from the beginning of the arry until the first'' successful match from the MatchGreetings function,'' returning the index the element was found at.Private Sub FindFirstGreeting() Debug.Print cArray.FindIndex(GetStrings, AddressOf MatchGreetings)End Sub'' Searches from the end of the array until the first'' successful match from the MatchGreetings function,'' returning the index the element was found at.Private Sub FindLastGreeting() Debug.Print cArray.FindLastIndex(GetStrings, AddressOf MatchGreetings)End Sub'' Finds all of the array elements that pass the criteria of the'' MatchGreetings function. The found elements are placed'' into a new array of the same datatype as the original array'' and returned.Private Sub FindAllGreetings() Dim a() As String a = cArray.FindAll(GetStrings, AddressOf MatchGreetings) Debug.Print a(0), a(1)End Sub'' Finds all of the array elements that pass the criteria of the'' MatchNonGreetings function. The found elements are placed'' into a new array of the same datatype as the original array'' and returned.Private Sub FindAllNonGreetings() Dim i As Long Dim a() As String a = cArray.FindAll(GetStrings, AddressOf MatchNonGreetings) For i = 0 To UBound(a) Debug.Print a(i), Next iEnd Sub'' Create a sample array of strings to search.Private Function GetStrings() As String() GetStrings = cArray.NewArray(ciString, "One", "Two", "Hello", "Four", "Hi", "Six")End Function'' Callback method used to match a string element from'' the array to the possible greetings we are searching for.'' The method signature should be a ByRef of the datatype'' of the specific array being searched.Public Function MatchGreetings(ByRef s As String) As Boolean MatchGreetings = ((s = "Hello") Or (s = "Hi"))End Function'' Callback method used to match a string element from'' the array to determine that we have matched against a non-greeting.'' The method signature should be a ByRef of the datatype'' of the specific array being searched.Public Function MatchNonGreetings(ByRef s As String) As Boolean MatchNonGreetings = Not ((s = "Hello") Or (s = "Hi"))End Function'' this code produces the following output.'''' 2'' 4'' Hello Hi'' One Two Four Six
Project VBCorLib Overview Class cArray Overview cArray Properties cArray Methods Exists FindAll