Removing the words from string

[lavanya uppala]

Hi sir this is lavanya. I am begginer in vb.net. I have a problem in deleting the first two words in a string. I am not using the loops.

[cgeier]

If you don't want to use a loop, you could use "Substring" and "IndexOf(" ").

[PerplexedB]

Frankly, I don't see how you can do this without a loop, but here is one solution :

 Sub Main()
        Console.WriteLine(removeFirstTwoWords("word1 word2 word3 word4"))
        Console.ReadKey()
    End Sub
    Function removeFirstTwoWords(s As String) As String
        Dim a() As String = Split(s, " ")
        Dim result As String = ""
        For i As Integer = 2 To a.Length - 1
            result &= IIf(i = 2, "", " ") & a(i)
        Next
        Return result
    End Function

[cgeier]

The easiest way to do it without using a loop is to use recursion. I will show you two recursive methods. The difference is the placement of the subtraction from the counter (numberOfWords = numberOfWords - 1). This determines whether you will use <= or just < in your "if" statement.

Note: The counter parameter numberOfWords must be passed using ByRef for this to work.

If we decrement after the "if" statement we do something like the following:

Version 1:

Private Function removeWords(ByVal userStr As String, ByRef numberOfWords As String)

    Dim retStr As String = String.Empty

    'if we decrement after this statement,
    'we use <= here
    If numberOfWords <= 0 Or userStr.Length = 0 Then
        Return userStr
    End If

                    ...

    'decrement counter
    numberOfWords = numberOfWords - 1

    'recursively call removeWords
    Return removeWords(retStr, numberOfWords)
End Function

removeWords function:

    Private Function removeWords(ByVal userStr As String, ByRef numberOfWords As String)
        Dim retStr As String = String.Empty

        'return the string when it is either
        'empty or the desired number of words
        'have been removed
        If numberOfWords <= 0 Or userStr.Length = 0 Then
            Return userStr
        End If

        'remove any leading or trailing spaces
        retStr = userStr.Trim()

        If retStr.Contains(" ") Then
            'string contains more than 1 word
            retStr = retStr.Substring(retStr.IndexOf(" ") + 1)
        Else
            'string contains only 1 word
            retStr = String.Empty
        End If

        'decrement counter
        numberOfWords = numberOfWords - 1

        'recursively call removeWords
        Return removeWords(retStr, numberOfWords)
    End Function

Version 2:
If we decrement before the "if" statement we do something like the following:

Private Function removeWords(ByVal userStr As String, ByRef numberOfWords As String)

    Dim retStr As String = String.Empty

    'decrement counter
    numberOfWords = numberOfWords - 1

    'if we decrement before this statement,
    'we use <
    If numberOfWords < 0 Or userStr.Length = 0 Then
        Return userStr
    End If

                      ...

    'recursively call removeWords
    Return removeWords(retStr, numberOfWords)
End Function

removeWords function:

    Private Function removeWords(ByVal userStr As String, ByRef numberOfWords As String)
        Dim retStr As String = String.Empty

        'decrement counter
        numberOfWords = numberOfWords - 1

        'return the string when it is either
        'empty or the desired number of words
        'have been removed
        If numberOfWords < 0 Or userStr.Length = 0 Then
            Return userStr
        End If

        'remove any leading or trailing spaces
        retStr = userStr.Trim()

        If retStr.Contains(" ") Then
            'string contains more than 1 word
            retStr = retStr.Substring(retStr.IndexOf(" ") + 1)
        Else
            'string contains only 1 word
            retStr = String.Empty
        End If

        'recursively call removeWords
        Return removeWords(retStr, numberOfWords)
    End Function

Usage:

Dim myStr As String = String.Empty

myStr = removeWords("word1 word2 word3 word4", 2)

[cgeier]

One more way to do it (without using a loop), is to create a method that removes one word, and call it repeatedly. Although, I advise against this method.

    Private Function removeWord(ByVal userStr As String)
        Dim retStr As String = userStr

        'remove any leading or trailing spaces
        retStr = userStr.Trim()

        If retStr.Contains(" ") Then
            'string contains more than 1 word
            retStr = retStr.Substring(retStr.IndexOf(" ") + 1)
        Else
            'string contains only 1 word
            retStr = String.Empty
        End If

        Return retStr
    End Function

Usage:
Dim myStr As String = String.Empty

'call 2 times to remove 2 words
myStr = removeWord(myStr)
myStr = removeWord(myStr)

[PerplexedB]

I stand corrected. This is doable without a loop. Cgeier, good thinking. :)