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Find and Replace a String in TextBox, ListBox and ComboBox


Tip Abstraction:
        Here you can search a text from a listbox, combobox or a multi line textbox.


Finding a particular string from a paragraph or from a list box is a common question arises in Visual Basic examination.

Search a string from paragraph of text

Here multiline textbox is used to type text and an input box accept search string. If the given string is found on the paragraph, then message box shows the result of search whether it is ‘Found’ or ‘Not found’.

   Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

Dim str As String

        str = InputBox("Enter the keyword to search")

        If TextBox1.Text.Contains(str) Then

            MessageBox.Show("Found")

        Else

            MessageBox.Show("Not found")

        End If

    End Sub

Search and replace a string from paragraph of text

Here an input box accept a string for search and if the given string is found on the paragraph, then another input box ask the string to replace first one.
Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

    Dim str As String
    Dim replceStr As String

        str = InputBox("Enter the keyword to search for replace")

        If TextBox1.Text.Contains(str) Then

            replceStr = InputBox("Enter the word for replace")

            TextBox1.Text = TextBox1.Text.Replace(str, replceStr)

        Else

            MessageBox.Show("Sorry, given string is not found")

        End If

    End Sub
Find and replace a string in vb

Searching an Item on List Box:

Here input box accept search text and a FOR loop continuously check every item on the listbox. The limit of the list box is the item count of the list box item. If an item matched with given search text, then a checker get a value 1 else the value will be 0. After the loop, program check the value of the checker variable. If it is 1, which means one of item matched.

Private Sub Button11_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button11.Click

        Dim str As String
       Dim i As Integer
        Dim position as Integer
        Dim checker As Integer = 0

        str = InputBox("Enter the keyword to search")  

        For i = 0 To ListBox1.Items.Count - 1

            If ListBox1.Items(i) = str Then

                checker = 1

                position = i + 1

                Exit For

            End If

        Next

        If checker = 1 Then   
           MessageBox.Show("The string " + str + " is found at positoin: " + position.ToString)
            checker = 0  
       Else        
           MessageBox.Show("Not Found")   
       End If    

    End Sub

VB search an item on listbox or combobox

Position denotes the position of the search text on the list box.
You can use almost these same codes for searching an item from ComboBox. Note that all above codes are not optimized and not completely error free.


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