CODEWITHSUNDEEP
vb.net
Minion
Minion

Reputation: 2567

Parsing string - "Contains" is insufficient

I use this code to check if a String is in another String:

If StringData(1).Contains("-SomeText2.") Then
    'some code
End If

'StringData(1) looks like this:
'-SomeText1.1401-|-SomeText2.0802-|-SomeText3.23-|-SomeText4.104-|
'In case I look for -SomeText1. I need 1401
'In case I look for -SomeText2. I need 0802
'In case I look for -SomeText3. I need 23
'In case I look for -SomeText4. I need 104

I first check if -SomeText2. is in StringData(1), and if it is, I need to get the next part of the text: 0802 which is the part I don't know how to do, how can I do it?

All the strings are separated by | and all substrings start and end with - and have a . separating the first part from the second. I check all the strings starting with - and ending with . because there are some with - and | in the middle, so Split function won't work.

Those strings change quite often, so I need something to check it no matter the length of the strings.

Upvotes: 0

Views: 96

Answers (2)

soohoonigan
soohoonigan

Reputation: 2350

I would just split the string up and get the text between "." and "-" when the search text is found like this:

    Dim str As String = "-SomeText1.1401-|-SomeText2.0802-|-SomeText3.23-|-SomeText4.104-"
    Dim searches() As String = {"-SomeText1", "-SomeText2", "-SomeText3", "-SomeText4"}
    For Each search As String In searches
        For Each value As String In str.Split(CChar("|"))
            If value.Contains(search) Then
                Dim partIwant As String = value.Substring(value.IndexOf(".") + 1, value.Length - value.IndexOf(".") - 2)
                MsgBox(partIwant)
                'Outputs: 1401, 0802, 23, 104
                Exit For
            End If
        Next
    Next

In this example, we just use Contains() to see if our search string is present or not...we can't actually use that function to get any further information because all it returns is a True or False. So once we know that our string has been found, it's just a matter of some string manipulation to grab the text between the "." and "-" characters. IndexOf() will get us the index of the period, and then we just pull the text between there and the last character of the string.

Upvotes: 3

Crusha K. Rool
Crusha K. Rool

Reputation: 1502

Your question has nothing to do with WPF, so the tag and title are misleading.

To solve your problem, you should use String.IndexOf(string) instead of String.Contains(string). That tells you at which position the given string starts. If that value is -1, it means that the original string does not contain your search string at all.

Once you have that starting index, you can use String.IndexOf(string, int) to search for the next occurrence of -, so you know where the entry stops. The second parameter tells it at which index it should start the search, and in this case you should start the search at the index where you found your first match.

Now that you know the starting index of your match, the end index of the entry and the length of your search string, you can put those together and easily use String.Substring(int, int) to get the part of the string that you are interested in.

That's the straight forward, naive solution. A more sophisticated solution would simply build a regular expression for the search string that is built in a way that the part you are interested in is included in the capture group. But that's a more elaborate topic.

Upvotes: 1

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