How to search only the first line of a multiline textbox in VB.NET-CodePudding

Is there any way to search only the first line of a Multiline Textbox without knowing exactly at what position the text is you're looking for?

If I knew the position of the text I was looking for I could do something like:

Dim myNotes As String = "The book has a lot of text"
Dim myText As String = "text"
If Not myNotes.Substring(0,4) = myText Then 
    ' Do Something
End If

Or if I wanted to search the entire textbox I could do something like:

Dim myNotes As String = "The book has a lot of text"
Dim myText As String = "text"
If Not myNotes.Contains(myText) Then 
    ' Do Something
End If

But I want to search only the first line of the textbox and I'm not sure at what position the text may be. Is there anyway to do a search like that?

CodePudding user response：

You could take the text and extract the first line.

int pos = text.IndexOfAny('\r', '\n');
if (pos >= 0)
    text = text.SubString(0, pos);

// text now contains only the first line

Then you can search the resulting string.

CodePudding user response：

This is another example of why you should ALWAYS read the relevant documentation. If you had read the documentation for the TextBox class then you'd know that it has a Lines property. To get the first line of text, you simply get the first element of that array:

Dim firstLine = myTextBox.Lines(0)

If Not filrstLine.Contains(myText) Then
    'Do something
End If

Note that this only applies where the user has explicitly added a line break to the text. I assume that that is what you want, given that you have accepted another answer that does the same thing. If you mean the first line based on automatic word-wrap then that requires a bit more effort.