I tried to make a quick-sort in VB2015, however when I run it, the values don't sort fully (however it does almost sort). I'm fairly sure that the problem has something to do with the two recurring lines.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
numbers = TextBox1.Text.Split()
Dim tempstring As String
Form2.Show()
tempstring = ""
quicksort(numbers, numbers.Length() - 1, 0)
For Each a As String In numbers
tempstring = tempstring + a + " "
Next
TextBox2.Text = tempstring
Form2.Show()
Form2.Chart1.Series(0).Points.DataBindY(numbers)
End Sub
Public Sub quicksort(list As Array, high As Integer, low As Integer)
MessageBox.Show(Str(high) + " " + Str(low))
ListView1.Items.Add(Str(high) + " " + Str(low))
Dim i As Integer
Dim pivot As Integer
'pivot = (high + low) / 2
pivot = high
If high > low + 1 And low >= 0 Then
i = low
For c = low + 1 To high
If Int(list(c)) <= Int(list(pivot)) Then
swap(list, c, i)
i = i + 1
End If
Next
quicksort(numbers, i - 2, low)
quicksort(numbers, high, i)
End If
End Sub
Public Sub swap(list As Array, x As Integer, y As Integer)
Dim temp As Integer
temp = list(x)
list(x) = list(y)
list(y) = temp
Form2.Chart1.Series(0).Points.DataBindY(numbers)
'pause()
End Sub
I know this is old, but somebody may come across this. Your SWAP sub needs to pass the parameters ByRef, or the swap is only taking place inside the sub's variables and not within your QuickSort routine.
Related
I am using vb6 and trying to generate a random number or String with this format
S1 = "378125649"
I have three requirements NO Duplicates Values & No Zeros & 9 charcters in length
I have approached This two very different ways the random number generator method is failing the FindAndReplace works but is too much code
The questions are
How to fix the GetNumber method code to meet the three requirement?
OR
How to simplify the FindAndReplace code to reflect a completely new sequence of numbers each time?
GetNumber code Below
Private Sub GetNumber()
Randomize
Dim MyRandomNumber As Long 'The chosen number
Dim RandomMax As Long 'top end of range to pick from
Dim RandomMin As Long 'low end of range to pick from
'Dim Kount As Long 'loop to pick ten random numbers
RandomMin = 1
RandomMax = 999999999
MyRandomNumber = Int(Rnd(1) * RandomMax) + RandomMin
lbOne.AddItem CStr(MyRandomNumber) & vbNewLine
End Sub
The FindAndReplace Code Below
Private Sub FindAndReplace()
Dim S4 As String
S4 = "183657429"
Dim T1 As String
Dim T2 As String
Dim J As Integer
Dim H As Integer
J = InStr(1, S4, 2)
H = InStr(1, S4, 8)
T1 = Replace(S4, CStr(J), "X")
T1 = Replace(T1, CStr(H), "F")
If Mid(T1, 8, 1) = "F" And Mid(T1, 2, 1) = "X" Then
T2 = Replace(T1, "F", "8")
T2 = Replace(T2, "X", "2")
End If
tbOne.Text = CStr(J) & " " & CStr(H)
lbOne.AddItem "Original Value " & S4 & vbNewLine
lbOne.AddItem "New Value " & T2 & vbNewLine
End Sub
Here's a way of generating 9-digit random numbers with no zeroes. The basic idea is to build a 9-character string position by position where each position is a random number between 1 and 9. Then each string is added to a collection to remove any duplicates. This code will generate 100,000 unique numbers:
Option Explicit
Private Sub Command1_Click()
Dim c As Collection
Set c = GetNumbers()
MsgBox c.Count
End Sub
Private Function GetNumbers() As Collection
On Error Resume Next
Dim i As Integer
Dim n As String
Randomize
Set GetNumbers = New Collection
Do While GetNumbers.Count < 100000
n = ""
For i = 1 To 9
n = n & Int((9 * Rnd) + 1)
Next
GetNumbers.Add n, n
Loop
End Function
In my testing, this code only generated 2 duplicates for the 100,000 unique numbers returned.
I don't have a VB6 compiler, so I winged it:
Function GetNumber(lowerLimit as Integer, upperLimit As Integer) As Integer
Dim randomNumber As String
Dim numbers As New Collection
Randomize
For i As Integer = lowerLimit To upperLimit
Call numbers.Add(i)
Next
For j As Integer = upperLimit To lowerLimit Step -1
Dim position As Short = Int(((j - lowerLimit)* Rnd) + 1)
randomNumber = randomNumber & numbers(position)
Call numbers.Remove(position)
Next
Return(CInt(randomNumber))
End Function
Use that function by calling for example:
GetNumber(1, 9)
I don't have VB6 on my machines anymore, so here's a solution written in Excel that shuffles the digits in 123456789 using an array.
You should be able to use it with little conversion:
Private Function RndNumber() As String
Dim i, j As Integer
Dim tmp As Variant
Dim digits As Variant
digits = Array("1", "2", "3", "4", "5", "6", "7", "8", "9")
For i = 0 To UBound(digits)
j = Int(9 * Rnd)
tmp = digits(i)
digits(i) = digits(j)
digits(j) = tmp
Next
RndNumber = Join(digits, "")
End Function
Here's a variation to play with that will shuffle an array you pass in and join them together with the specified separator. Note that the arrays being passed in are of variant type so anything can be shuffled. The first array has numbers while the second array has strings:
Private Sub Foo()
Dim digits As Variant
digits = Array(1, 2, 3, 4, 5, 6, 7, 8, 9)
Dim rndNnumber As String
RndNumber = ShuffleArrayAndJoin(digits, "")
Debug.Print RndNumber
Dim pets As Variant
pets = Array("cat", "dog", "fish", "hamster")
Dim rndPets As String
rndPets = ShuffleArrayAndJoin(pets, ", ")
Debug.Print (rndPets)
End Sub
Private Function ShuffleArrayAndJoin(ByVal sourceArray As Variant, ByVal separator As String) As String
Dim i, j As Integer
Dim tmp As Variant
For i = 0 To UBound(sourceArray)
j = Int(UBound(sourceArray) * Rnd)
tmp = sourceArray(i)
sourceArray(i) = sourceArray(j)
sourceArray(j) = tmp
Next
ShuffleArrayAndJoin = Join(sourceArray, separator)
End Function
Function GetNumber() As String
Dim mNum As String
Randomize Timer
Do While Len(mNum) <> 9
mNum = Replace(Str(Round(Rnd(Timer), 6)) + Str(Round(Rnd(Timer), 3)), " .", "")
Loop
GetNumber = mNum
End Function
Been clicking a button to load a text box for a couple of minutes, but so far no dupes, and I'd bet money there never will be any..
Well, it solves just 1 problem: it will never ever repeat number
but it has to be 15+ numbers long...
Function genRndNr(nrPlaces) 'must be more then 10
Dim prefix As String
Dim suffix As String
Dim pon As Integer
prefix = Right("0000000000" + CStr(DateDiff("s", "2020-01-01", Now)), 10)
suffix = Space(nrPlaces - 10)
For pon = 1 To Len(suffix)
Randomize
Randomize Rnd * 1000000
Mid(suffix, pon, 1) = CStr(Int(Rnd * 10))
Next
genRndNr = prefix + suffix
End Function
Using SNMP version 3, I am creating a user.
Right now, I have it set up where I clone a user and that works just fine. However, I need to change the new user's authKey. How can I do this? I know the oid for authKeyChange, however, I don't know how to generate the new key. How do I generate that key? Can it be done using SNMPSharpNet?
If there is an easier way to do this while I'm creating the user, I can do that as well. ANY way to change the authKey (and privKey, but one step at a time) is much appreciated. I'm using VB.net if it means anything.
So I've figured out how to do this. It's a bit of a complex process. I followed this document, which is rfc2574. Do a ctrl+F for "keyChange ::=" and you'll find the paragraph walking you through the algorithm to generate the keyChange value. The following code has worked reliably to generate the keyChange value. All you have to do from this point is push the keyChange value to the usmAuthKeyChange OID. If you are changing the privacy password, you push the keyChange value to the usmPrivKeyChange OID. I'm ashamed to say that due to the time crunch, I did not have time to make this work completely, so when using SHA, I had to code an entirely new method that did almost the exact same thing. Again, I'm ashamed to post it, but I know how much I was banging my head against a wall, and if someone comes here later and sees this, I would like them to know what to do without going through the struggle.
Here is all of the code you need using VB.Net and the SNMPSharpNet library:
Private Function GenerateKeyChange(ByVal newPass As String, ByVal oldPass As String, ByRef target As UdpTarget, ByRef param As SecureAgentParameters) As Byte()
Dim authProto As AuthenticationDigests = param.Authentication
Dim hash As IAuthenticationDigest = Authentication.GetInstance(authProto)
Dim L As Integer = hash.DigestLength
Dim oldKey() As Byte = hash.PasswordToKey(Encoding.UTF8.GetBytes(oldPass), param.EngineId)
Dim newKey() As Byte = hash.PasswordToKey(Encoding.UTF8.GetBytes(newPass), param.EngineId)
Dim random() As Byte = Encoding.UTF8.GetBytes(GenerateRandomString(L))
Dim temp() As Byte = oldKey
Dim delta(L - 1) As Byte
Dim iterations As Integer = ((newKey.Length - 1) / L) - 1
Dim k As Integer = 0
If newKey.Length > L Then
For k = 0 To iterations
'Append random to temp
Dim merged1(temp.Length + random.Length - 1) As Byte
temp.CopyTo(merged1, 0)
random.CopyTo(merged1, random.Length)
'Store hash of temp in itself
temp = hash.ComputeHash(merged1, 0, merged1.Length)
'Generate the first 16 values of delta
For i = 0 To L - 1
delta(k * L + i) = temp(i) Xor newKey(k * L + i)
Next
Next
End If
'Append random to temp
Dim merged(temp.Length + random.Length - 1) As Byte
temp.CopyTo(merged, 0)
random.CopyTo(merged, temp.Length)
'Store hash of temp in itself
temp = hash.ComputeHash(merged, 0, merged.Length)
'Generate the first 16 values of delta
For i = 0 To (newKey.Length - iterations * L) - 1
delta(iterations * L + i) = temp(i) Xor newKey(iterations * L + i)
Next
Dim keyChange(delta.Length + random.Length - 1) As Byte
random.CopyTo(keyChange, 0)
delta.CopyTo(keyChange, random.Length)
Return keyChange
End Function
Private Function GenerateKeyChangeShaSpecial(ByVal newPass As String, ByVal oldPass As String, ByRef target As UdpTarget, ByRef param As SecureAgentParameters) As Byte()
Dim authProto As AuthenticationDigests = param.Authentication
Dim hash As IAuthenticationDigest = Authentication.GetInstance(authProto)
Dim L As Integer = 16
Dim oldKey() As Byte = hash.PasswordToKey(Encoding.UTF8.GetBytes(oldPass), param.EngineId)
Dim newKey() As Byte = hash.PasswordToKey(Encoding.UTF8.GetBytes(newPass), param.EngineId)
Array.Resize(oldKey, L)
Array.Resize(newKey, L)
Dim random() As Byte = Encoding.UTF8.GetBytes(GenerateRandomString(L))
Dim temp() As Byte = oldKey
Dim delta(L - 1) As Byte
Dim iterations As Integer = ((newKey.Length - 1) / L) - 1
Dim k As Integer = 0
If newKey.Length > L Then
For k = 0 To iterations
'Append random to temp
Dim merged1(temp.Length + random.Length - 1) As Byte
temp.CopyTo(merged1, 0)
random.CopyTo(merged1, random.Length)
'Store hash of temp in itself
temp = hash.ComputeHash(merged1, 0, merged1.Length)
Array.Resize(temp, L)
'Generate the first 16 values of delta
For i = 0 To L - 1
delta(k * L + i) = temp(i) Xor newKey(k * L + i)
Next
Next
End If
'Append random to temp
Dim merged(temp.Length + random.Length - 1) As Byte
temp.CopyTo(merged, 0)
random.CopyTo(merged, temp.Length)
'Store hash of temp in itself
temp = hash.ComputeHash(merged, 0, merged.Length)
Array.Resize(temp, L)
'Generate the first 16 values of delta
For i = 0 To (newKey.Length - iterations * L) - 1
delta(iterations * L + i) = temp(i) Xor newKey(iterations * L + i)
Next
Dim keyChange(delta.Length + random.Length - 1) As Byte
random.CopyTo(keyChange, 0)
delta.CopyTo(keyChange, random.Length)
Return keyChange
End Function
Private Function GenerateRandomString(ByVal length As Integer) As String
Dim s As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
Dim r As New Random
Dim sb As New StringBuilder
For i As Integer = 1 To length
Dim idx As Integer = r.Next(0, 51)
sb.Append(s.Substring(idx, 1))
Next
Return sb.ToString()
End Function
Again, I am oh so well aware this code is hideous, but it works, and that is all I needed in the meantime. I understand this is technical debt and not the way I should code, but it's here and I hope you can get some use out of it.
If this doesn't work, don't forget to go to frc2574 and look at the algorithm.
Suppose I want to build the bit mask with the Nth bit set. I have N as an integer.
Which is better? 1 << N or a lookup table (pointer arithmetic addition)?
My guess is that a single bit shift operation is faster than a memory lookup, and only once cache-hot does LUT have a fighting chance. However if this is the case then why are LUT's so often the fastest solution in bit-twiddling problems? Is it simply because of the huge caches we have in our CPU's these days?
Let me qualify the question with the fact that I care the most about this operation at this moment on x86-64.
A bit shift will always be far faster than either a look-up table or a calc.
Are you sure? I ran this VB program and the results were a bit variable, but lookup was usually quicker than bit shifting, and not much higher than the null time. This is probably because of caching, so it's hard to generalise from this.
I got a similar result from a random shift value, but of course the random number generation was taking longer than anything else.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim SW As New Stopwatch()
Dim TimeShift As Long
Dim TimeLookUp As Long
Dim Timenull As Long
Dim i As Integer
Dim j As Integer
Dim Bit As UInteger
Dim R As New Random()
Dim total As UInteger
Dim S = New System.Text.StringBuilder()
total = 0
SW.Start()
j = 0
For i = 1 To RepCount
Bit = CUInt(1) << (j And 31)
j += 1
'Bit = 1 << (R.Next(31))
total = total Or Bit
Next
SW.Stop()
TimeShift = SW.ElapsedMilliseconds
SW.Reset()
SW.Start()
For i = 1 To RepCount
Bit = Bits(j And 31)
j += 1
'Bit = Bits(R.Next(31))
total = total Or Bit
Next
SW.Stop()
TimeLookUp = SW.ElapsedMilliseconds
SW.Reset()
SW.Start()
For i = 1 To RepCount
total = total Or (j And 31)
j += 1
Next
SW.Stop()
Timenull = SW.ElapsedMilliseconds
If Stopwatch.IsHighResolution Then
S.Append("High")
Else
S.Append("Low")
End If
S.Append(" frequency clock")
S.AppendLine()
S.Append("Shift time= " & TimeShift & " ms")
S.AppendLine()
S.Append("Lookup time= " & TimeLookUp & " ms")
S.AppendLine()
S.Append("Null time=" & Timenull & " ms")
S.AppendLine()
S.Append("Total= " & total.ToString)
MsgBox(S.ToString)
End Sub
End Class
I have been asked to ask this question again and in a little different context. This is the previous post:
Filtering in VBA after finding combinations
I would like to make this code possible with 100 different variables without having excel run out of memory and reducing the execution time significantly.
The problem with the code below is that if I have 100 boxes, excel will run out of memory in the line "Result(0 To 2 ^ NumFields - 2)" ( The code works for < 10 boxes)
This is my input:
3 A B C D E ...
7.7 3 1 1 1 2 ...
5.5 2 1 2 3 3 ...
This is the code:
Function stackBox()
Dim ws As Worksheet
Dim width As Long
Dim height As Long
Dim numOfBox As Long
Dim optionsA() As Variant
Dim results() As Variant
Dim str As String
Dim outputArray As Variant
Dim i As Long, j As Long
Dim currentSymbol As String
'------------------------------------new part----------------------------------------------
Dim maxHeight As Double
Dim maxWeight As Double
Dim heightarray As Variant
Dim weightarray As Variant
Dim totalHeight As Double
Dim totalWeight As Double
'------------------------------------new part----------------------------------------------
Set ws = Worksheets("Sheet1")
With ws
'clear last time's output
height = .Cells(.Rows.Count, 1).End(xlUp).row
If height > 3 Then
.Range(.Cells(4, 1), .Cells(height, 1)).ClearContents
End If
numOfBox = .Cells(1, 1).Value
width = .Cells(1, .Columns.Count).End(xlToLeft).Column
If width < 2 Then
MsgBox "Error: There's no item, please fill your item in Cell B1,C1,..."
Exit Function
End If
'------------------------------------new part----------------------------------------------
maxHeight = .Cells(2, 1).Value
maxWeight = .Cells(3, 1).Value
ReDim heightarray(1 To 1, 1 To width - 1)
ReDim weightarray(1 To 1, 1 To width - 1)
heightarray = .Range(.Cells(2, 2), .Cells(2, width)).Value
weightarray = .Range(.Cells(3, 2), .Cells(3, width)).Value
'------------------------------------new part----------------------------------------------
ReDim optionsA(0 To width - 2)
For i = 0 To width - 2
optionsA(i) = .Cells(1, i + 2).Value
Next i
GenerateCombinations optionsA, results, numOfBox
' copy the result to sheet only once
ReDim outputArray(1 To UBound(results, 1) - LBound(results, 1) + 1, 1 To 1)
Count = 0
For i = LBound(results, 1) To UBound(results, 1)
If Not IsEmpty(results(i)) Then
'rowNum = rowNum + 1
str = ""
totalHeight = 0#
totalWeight = 0#
For j = LBound(results(i), 1) To UBound(results(i), 1)
currentSymbol = results(i)(j)
str = str & currentSymbol 'results(i)(j) is the SYMBOL e.g. A, B, C
'look up box's height and weight , increment the totalHeight/totalWeight
updateParam currentSymbol, optionsA, heightarray, weightarray, totalHeight, totalWeight
Next j
If totalHeight < maxHeight And totalWeight < maxWeight Then
Count = Count + 1
outputArray(Count, 1) = str
End If
'.Cells(rowNum, 1).Value = str
End If
Next i
.Range(.Cells(4, 1), .Cells(UBound(outputArray, 1) + 3, 1)).Value = outputArray
End With
End Function
Sub updateParam(ByRef targetSymbol As String, ByRef symbolArray As Variant, ByRef heightarray As Variant, ByRef weightarray As Variant, ByRef totalHeight As Double, ByRef totalWeight As Double)
Dim i As Long
Dim index As Long
index = -1
For i = LBound(symbolArray, 1) To UBound(symbolArray, 1)
If targetSymbol = symbolArray(i) Then
index = i
Exit For
End If
Next i
If index <> -1 Then
totalHeight = totalHeight + heightarray(1, index + 1)
totalWeight = totalWeight + weightarray(1, index + 1)
End If
End Sub
Sub GenerateCombinations(ByRef AllFields() As Variant, _
ByRef Result() As Variant, ByVal numOfBox As Long)
Dim InxResultCrnt As Integer
Dim InxField As Integer
Dim InxResult As Integer
Dim i As Integer
Dim NumFields As Integer
Dim Powers() As Integer
Dim ResultCrnt() As String
NumFields = UBound(AllFields) - LBound(AllFields) + 1
ReDim Result(0 To 2 ^ NumFields - 2) ' one entry per combination
ReDim Powers(0 To NumFields - 1) ' one entry per field name
' Generate powers used for extracting bits from InxResult
For InxField = 0 To NumFields - 1
Powers(InxField) = 2 ^ InxField
Next
For InxResult = 0 To 2 ^ NumFields - 2
' Size ResultCrnt to the max number of fields per combination
' Build this loop's combination in ResultCrnt
ReDim ResultCrnt(0 To NumFields - 1)
InxResultCrnt = -1
For InxField = 0 To NumFields - 1
If ((InxResult + 1) And Powers(InxField)) <> 0 Then
' This field required in this combination
InxResultCrnt = InxResultCrnt + 1
ResultCrnt(InxResultCrnt) = AllFields(InxField)
End If
Next
If InxResultCrnt = 0 Then
Debug.Print "testing"
End If
'additional logic here
If InxResultCrnt >= numOfBox Then
Result(InxResult) = Empty
Else
' Discard unused trailing entries
ReDim Preserve ResultCrnt(0 To InxResultCrnt)
' Store this loop's combination in return array
Result(InxResult) = ResultCrnt
End If
Next
End Sub
Here's a version that does all the heavy lifting in variant arrays
(Combinations logic based on this answer for This Answer by Joubarc)
This runs on a sample dataset of 100 boxes with > 40,000 returned, and in < 1 second
Notes:
Execution time rises quickly if the Max number of boxes increases (eg 4 from 100: approx 13s)
If the number of returned results exceeds 65535, the code to tranpose the array into the sheet fails (last line of the sub) If you need to handle this may results, you will need to change the way results are returned to the sheet
Sub Demo()
Dim rNames As Range
Dim rHeights As Range
Dim rWeights As Range
Dim aNames As Variant
Dim aHeights As Variant
Dim aWeights As Variant
Dim MaxNum As Long
Dim MaxHeight As Double
Dim MaxWeight As Double
' *** replace these six line with your data ranges
Set rNames = Range([F5], [F5].End(xlToRight))
Set rHeights = rNames.Offset(1, 0)
Set rWeights = rNames.Offset(2, 0)
MaxNum = [C5]
MaxHeight = [C6]
MaxWeight = [C7]
aNames = rNames
aHeights = rHeights
aWeights = rWeights
Dim Result() As Variant
Dim n As Long, m As Long
Dim i As Long, j As Long
Dim iRes As Long
Dim res As String
Dim TestCombin() As Long
Dim TestWeight As Double
Dim TestHeight As Double
Dim idx() As Long
' Number of boxes
ReDim TestCombin(0 To MaxNum - 1)
n = UBound(aNames, 2) - LBound(aNames, 2) + 1
' estimate size of result array = number of possible combinations
For m = 1 To MaxNum
i = i + Application.WorksheetFunction.Combin(n, m)
Next
ReDim Result(1 To 3, 1 To i)
' allow for from 1 to MaxNum of boxes
iRes = 1
For m = 1 To MaxNum
ReDim idx(0 To m - 1)
For i = 0 To m - 1
idx(i) = i
Next i
Do
'Test current combination
res = ""
TestWeight = 0#
TestHeight = 0#
For j = 0 To m - 1
'Debug.Print aNames(1, idx(j) + 1);
res = res & aNames(1, idx(j) + 1)
TestWeight = TestWeight + aWeights(1, idx(j) + 1)
TestHeight = TestHeight + aHeights(1, idx(j) + 1)
Next j
'Debug.Print
If TestWeight <= MaxWeight And TestHeight <= MaxHeight Then
Result(1, iRes) = res
' optional, include actual Height and Weight in result
Result(2, iRes) = TestHeight
Result(3, iRes) = TestWeight
iRes = iRes + 1
End If
' Locate last non-max index
i = m - 1
While (idx(i) = n - m + i)
i = i - 1
If i < 0 Then
'All indexes have reached their max, so we're done
Exit Do
End If
Wend
'Increase it and populate the following indexes accordingly
idx(i) = idx(i) + 1
For j = i To m - 1
idx(j) = idx(i) + j - i
Next j
Loop
Next
' Return Result to sheet
Dim rng As Range
ReDim Preserve Result(1 To 3, 1 To iRes)
' *** Adjust returnm range to suit
Set rng = [E10].Resize(UBound(Result, 2), UBound(Result, 1))
rng = Application.Transpose(Result)
End Sub
Looking for the best way to do this in VB6. Typically, I would use this approach...
' count spaces
For i = 1 To Len(text)
If Mid$(text, i, 1) = " " Then count = count + 1
Next
Not saying it's the best way, but you code do:
distinctChr = " "
count = Len(text) - Len(Replace(text, distinctChr , ""))
Use the split command like this
Dim TempS As String
TempS = " This is a split test "
Dim V As Variant
V = Split(TempS, " ")
Cls
Print UBound(V) '7
V = Split(TempS, "i")
Print UBound(V) '3
V = Split(TempS, "e")
Print UBound(V) '1
You can combine it to a single line.
Print UBound(Split(TempS, "i"))
I did some crude timing on it. On a 40,000 character string with all spaces it seems to clock in at 17 milliseconds on a 2.4 GHz Intel Core 2 processor.
A function could look like this
Function CountChar(ByVal Text As String, ByVal Char As String) As Long
Dim V As Variant
V = Split(Text, Char)
CountChar = UBound(V)
End Function
I would use a modified bucket sort:
Dim i as Integer
Dim index As Integer
Dim count as Integer
Dim FoundByAscii(0 To 255) As Boolean
For i = 1 To Len(text)
index = Asc(Mid$(text, i, 1))
FoundByAscii(index) = True
Next i
count = 0
For i = 0 To 255
If FoundByAscii(i) Then
count = count + 1
End If
Next i
...and your result is in count. The performance is O(N) - if Mid$ is O(1).
Edit:
Based on your clarification, do this:
' count spaces
Dim asciiToSearchFor As Integer
asciiToSearchFor = Asc(" ")
For i = 1 To Len(text)
If Asc(Mid$(text, i, 1)) = asciiToSearchFor Then count = count + 1
Next
As ascii compares have to be faster that string comparison. I'd profile it just in case, but I'm pretty sure.
It's not clear what you mean by the best way to do this.
If you want something very fast, but totally unmaintainable, adapt this horrible code that delves into the underlying memory of a VB6 string to count the number of words. Courtesy of VBspeed.