How can I search texts inside a lot of specific labels and the color of the searched texts would appear in red

Question

I have the following code (credit to Chetan Ranpariya) but is not working. It gives the following error:

Additional information: Object reference not set to an instance of an object.

Inherits Form  
Private labels As List(Of Label)  
    Public Sub New2()  
        InitializeComponent()  
        labels = New List(Of Label)()  

        labels.Add(Label29)  
        labels.Add(Label30)  
        labels.Add(Label31)  
        labels.Add(Label34)  
        labels.Add(Label35)  
        labels.Add(Label36)  
        labels.Add(Label37)  

        labels.Add(Label38)  
        labels.Add(Label39)  
        labels.Add(Label44)  
        labels.Add(Label45)  
        labels.Add(Label47)  
        labels.Add(Label51)  
        labels.Add(Label65)  

        labels.Add(Label66)  
        labels.Add(Label67)  
        labels.Add(Label68)  
        labels.Add(Label69)  
        labels.Add(Label70)  
        labels.Add(Label83)  
        labels.Add(Label85)  

        labels.Add(Label86)  
        labels.Add(Label87)  
        labels.Add(Label88)  
        labels.Add(Label92)  
        labels.Add(Label93)  
        labels.Add(Label94)  

    End Sub  

    Private Sub Button30_Click(sender As Object, e As EventArgs) Handles Button30.Click  
        For Each var As Label In labels  
            If TextBox1.Text = var.Text Then  
                var.ForeColor = Color.Red  
            End If  
        Next  
    End Sub  

Somebody please help. Thank you.

Answer 1

Here is another option and is case insensitive

Public Class Form1  
    Private ReadOnly LabelList As New List(Of Label)  
  
    Private Sub Form1_Shown(sender As Object, e As EventArgs) Handles Me.Shown  
  
        LabelList.AddRange(New Label() _  
            {  
                Label1,  
                Label2,  
                Label3,  
                Label4,  
                Label5,  
                Label6  
            })  
  
    End Sub  
  
    Private Sub WorkButton_Click(sender As Object, e As EventArgs) Handles WorkButton.Click  
  
        If LabelList.Any(Function(currentLabel) ItemTextBox.Text.Equals(currentLabel.Text, StringComparison.CurrentCultureIgnoreCase)) Then  
            LabelList.ForEach(  
                Sub(label)  
                    If label.Text.Equals(ItemTextBox.Text, StringComparison.CurrentCultureIgnoreCase) Then  
                        label.ForeColor = Color.Red  
                    End If  
                End Sub)  
        End If  
    End Sub  
End Class  
  

Update

Using case insensitive compare

Public Module StringExtensions  
    <Runtime.CompilerServices.Extension>  
    Public Function ContainsInsensitive(source As String, toCheck As String) As Boolean  
        Return source.IndexOf(toCheck, StringComparison.OrdinalIgnoreCase) >= 0  
    End Function  
End Module  

Form code

Public Class Form1  
    Private ReadOnly LabelList As New List(Of Label)  
  
    Private Sub Form1_Shown(sender As Object, e As EventArgs) Handles Me.Shown  
  
        LabelList.AddRange(New Label() _  
            {  
                Label1,  
                Label2,  
                Label3,  
                Label4,  
                Label5,  
                Label6  
            })  
  
    End Sub  
  
    Private Sub WorkButton_Click(sender As Object, e As EventArgs) Handles WorkButton.Click  
  
        If LabelList.Any(Function(currentLabel) currentLabel.Text.ContainsInsensitive(ItemTextBox.Text)) Then  
            LabelList.ForEach(  
                Sub(label)  
                    If label.Text.ContainsInsensitive(ItemTextBox.Text) Then  
                        label.ForeColor = Color.Red  
                    End If  
                End Sub)  
        End If  
  
    End Sub  
End Class  

Answer 2

Okay, as mentioned before you should make an attempt at changing the code.

For instance, you are right, when there are multiple words, nothing, zilch but if we think about it the change is clear, we need to split the words from the search string. This I've done and works as shown below but there are other requirements such as case sensitivity which may need modifications.

New code sample is here. I don't have time to fully test so I suggest you take time and make this a learning exercise :-)

https://github.com/karenpayneoregon/windows-forms-csharp/tree/master/Labels

Answer 3

Try renaming New2 to New.