String instance count

[Jon]

I want to count the number of instances of a certain string(delimite r) in
another string. I didn't see a function to do this in the framework (if
there is, please point me to it). If not, could someone let me know if the
method I've used below is efficient or if there is a better way to do it, as
these will be rather large strings I'm searching in. Thanks

Public Shared Function CountDelimiter( ByVal strInput As String, ByVal
strDelimiter As String) As Int32
Dim iStart As Int32, iCount As Int32, iResult As Int32

'Set our vars to base values
iStart = 1
iCount = 0

Do
'iResult becomes the position where delimiter is found. If 0, not
found.
iResult = InStr(iStart, strInput, strDelimiter)
If iResult = 0 Then Exit Do
'Increment our count var for each time it is found
iCount += 1
'Increment our next start position to be the next char after the
currently found position
iStart = iResult + 1
Loop

Return iCount
End Function

--
--------
Jon Rosenberg

[Chris Dunaway]

"Jon" <ru******@msn.c om> wrote in
news:vn******** ****@corp.super news.com:

I want to count the number of instances of a certain string(delimite r)

One method would be to use a regular expression and then check the
Matches.Count property:
'\\\\
Dim sSource As String = "abbabaabbababa babbababbabbaab ababbbabbababab babab"
Dim rx As New System.Text.Reg ularExpressions .Regex("a")

MsgBox("Number of matches = " & CStr(rx.Matches (sSource).Count ))
'////

[therealpmuk]

I also have an interest in this, needing to check for (and count) the number of occurrences of various errors in an error.log file.

The files can get quite large, but I have achieved the following results with a filesize of just over 11 Meg:-


Count 79608

TimeBySplit 22187500 Long
TimeByLoop 28750000 Long
TimeByRegEx 1093750 Long


Count 113

TimeBySplit 2031250 Long
TimeByLoop 28125000 Long
TimeByRegEx 156250 Long

Timing done using System.DateTime .Now.Ticks.

As you can see, the Regular Expression method consistently yields the fastest results.