how many times a string appears in another string

codes like(x is variable)


dim k as string="5b5" & x & "85"

I want to know how many times "5" appears in k,thanks

Quote:

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Originally Posted by vbsunst

codes like(x is variable)


dim k as string="5b5" & x & "85"

I want to know how many times "5" appears in k,thanks

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try this. i know my way is not best way. but you can refer it.

Code:

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  Dim a As Integer = 0
        Dim k As String = "5b585"
        For i As Integer = 0 To Len(k) - 1
            If k.Substring(i, 1).Contains("5") = True Then
                a = a + 1
            End If
        Next
        MsgBox("numbers of 5 is : " & a, MsgBoxStyle.Information, "info")

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hey vbsunst
you may use following

Code:

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Dim sText As String = "5b585"
                Dim cMatch as String = "5"
                Dim nCount as Integer
                For Each sT As String In  sText.ToCharArray()
                        If sT = cMatch Then
                                nCount=nCount+1               
                        End If
                Next
                MessageBox.Show(nCount)

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I would go for regular expressions

Code:

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Dim regx As New System.Text.RegularExpressions.Regex("5")
        Dim str As String = "1251werwer2225555"
        Dim Count As Integer = 0
        If regx.IsMatch(str) Then
            Count = regx.Matches(str).Count
        End If
        MessageBox.Show(Count)

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Code:

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Public Function StringCount(ByVal search As String, ByVal find As String) As Integer
    If String.IsNullOrEmpty(search) OrElse String.IsNullOrEmpty(find) Then
        Return 0
    End If

    Dim index As Integer = -1
    Dim count As Integer = -1
    Do
        index = search.IndexOf(find, index + 1, StringComparison.CurrentCultureIgnoreCase)
        count += 1
    Loop While index > -1
    Return count
End Function

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Oops I accidently posted this twice. Anyway this is just a function that counts the occurrences of a string using the built-in IndexOf and only searches after the last occurrence of the string so it should be pretty efficient. Also it ignores case using the current culture. You could easily add the culture as another parameter.

Edit:
Additionally, this will work for searching whole strings and not just a single character in a string. The functions above look like they will only work for a single character.

Example usage:
Dim count As Integer = StringCount("5b585", "5")

Code:

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Public Function StringCount(ByVal search As String, ByVal find As String) As Integer
    If String.IsNullOrEmpty(search) OrElse String.IsNullOrEmpty(find) Then
        Return 0
    End If

    Dim index As Integer = -1
    Dim count As Integer = -1
    Do
        index = search.IndexOf(find, index + 1, StringComparison.CurrentCultureIgnoreCase)
        count += 1
    Loop While index > -1
    Return count
End Function

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You can use LINQ for this to do a count, no need for loops.

Code:

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        Dim MatchingCharCount = Aggregate C As Char In k _
                                Where C = "5" _
                                Into Count()

        MessageBox.Show("5 was found: " & MatchingCharCount & " times")

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EDIT: sorry I did not see you were using VS2005. LINQ is in VS2008.