ComboBox.FindStringExact Method (String, Int32)


Finds the first item after the specified index that matches the specified string.

Namespace:   System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

Public Function FindStringExact (
	s As String,
	startIndex As Integer
) As Integer


Type: System.String

The String to search for.

Type: System.Int32

The zero-based index of the item before the first item to be searched. Set to -1 to search from the beginning of the control.

Return Value

Type: System.Int32

The zero-based index of the first item found; returns -1 if no match is found, or 0 if the s parameter specifies Empty.

Exception Condition

The startIndex is less than -1.


The startIndex is equal to the last index in the collection.

The search performed by this method is not case-sensitive. The s parameter is a string to compare against the text associated with the items in the combo box list. The search looks for a match starting from the beginning of the text, returning the first item in the list that matches the specified substring. You can then perform tasks, such as removing the item that contains the search text using the Remove method or changing the item's text. This method is typically used after a call has been made using the version of this method that does not specify a starting index. Once an initial item has been found in the list, this method is typically used to find further instances of the search text by specifying the index position in the startIndex parameter of the item after the first found instance of the search text. If you want to perform partial word search instead of an exact word match, use the FindString method.

The search performed by this method is circular. Although the search starts at the next index after the startIndex parameter, the search restarts at 0 when the end of the collection is reached. However, note that if the startIndex parameter itself is equal to the last index in the collection, an exception is thrown.

The following code example demonstrates how to initialize a ComboBox control by setting the MaxDropDownItems and DropDownStyle properties and using the FindStringExact methods to search the ComboBox. It also shows handling the SelectedIndexChanged event.

Imports System.Windows.Forms

Public Class Form1
    Inherits System.Windows.Forms.Form

    Public Sub New()
        Me.Label1 = New System.Windows.Forms.Label
        Me.Label1.Location = New System.Drawing.Point(8, 24)
        Me.Label1.Name = "Label1"
        Me.Label1.Size = New System.Drawing.Size(120, 32)
        Me.Label1.TabIndex = 1
        Me.Label1.Text = "Use drop-down to choose a name:"
        Me.Label1.TextAlign = System.Drawing.ContentAlignment.MiddleRight
        Me.ClientSize = New System.Drawing.Size(292, 266)
        Me.Name = "Form1"
        Me.Text = "Form1"
    End Sub

    Shared Sub Main()
        Application.Run(New Form1)
    End Sub

    Friend WithEvents Label1 As System.Windows.Forms.Label

    ' Declare and initialize the text box.
    ' This text box text will be update programmatically. The user is not 
    ' allowed to update it, so the ReadOnly property is set to true.
    Friend WithEvents TextBox1 As System.Windows.Forms.TextBox

    Private Sub InitializeTextBox()
        Me.TextBox1 = New System.Windows.Forms.TextBox
        Me.TextBox1.ScrollBars = ScrollBars.Vertical
        Me.TextBox1.Location = New System.Drawing.Point(64, 128)
        Me.TextBox1.Multiline = True
        Me.TextBox1.Name = "TextBox1"
        Me.TextBox1.ReadOnly = True
        Me.TextBox1.Size = New System.Drawing.Size(184, 120)
        Me.TextBox1.TabIndex = 4
        Me.TextBox1.Text = "Employee and Number of Awards:"
    End Sub

    ' Declare comboBox1 as a ComboBox.
    Friend WithEvents ComboBox1 As System.Windows.Forms.ComboBox

    ' This method initializes the combo box, adding a large string 
    ' array but limiting the drop-down size to six rows so the combo box
    ' doesn't cover other controls when it expands.
    Private Sub InitializeComboBox()
        Me.ComboBox1 = New System.Windows.Forms.ComboBox
        Dim employees() As String = New String() {"Hamilton, David", _
            "Hensien, Kari", "Hammond, Maria", "Harris, Keith", _
            "Henshaw, Jeff D.", "Hanson, Mark", "Harnpadoungsataya, Sariya", _
            "Harrington, Mark", "Harris, Keith", "Hartwig, Doris", _
            "Harui, Roger", "Hassall, Mark", "Hasselberg, Jonas", _
            "Harnpadoungsataya, Sariya", "Henshaw, Jeff D.", "Henshaw, Jeff D.", _
            "Hensien, Kari", "Harris, Keith", "Henshaw, Jeff D.", _
            "Hensien, Kari", "Hasselberg, Jonas", "Harrington, Mark", _
            "Hedlund, Magnus", "Hay, Jeff", "Heidepriem, Brandon D."}

        Me.ComboBox1.Location = New System.Drawing.Point(136, 32)
        Me.ComboBox1.IntegralHeight = False
        Me.ComboBox1.MaxDropDownItems = 5
        Me.ComboBox1.DropDownStyle = ComboBoxStyle.DropDown
        Me.ComboBox1.Name = "ComboBox1"
        Me.ComboBox1.Size = New System.Drawing.Size(136, 81)
        Me.ComboBox1.TabIndex = 0
    End Sub

    ' This method is called when the user changes his or her selection.
    ' It searches for all occurrences of the selected employee's
    ' name in the Items array and adds the employee's name and 
    ' the number of occurrences to TextBox1.Text.

    ' CAUTION   This code exposes a known bug: If the index passed to the 
    ' FindStringExact(searchString, index) method is the last index 
    ' of the array, the code throws an exception.
    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As Object, _
        ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged

        Dim comboBox As comboBox = CType(sender, comboBox)

        ' Save the selected employee's name, because we will remove
        ' the employee's name from the list.
        Dim selectedEmployee = CType(ComboBox1.SelectedItem, String)

        Dim count As Integer = 0
        Dim resultIndex As Integer = -1

        ' Call the FindStringExact method to find the first 
        ' occurrence in the list.
        resultIndex = ComboBox1.FindStringExact(ComboBox1.SelectedItem)

        ' Remove the name as it is found, and increment the found count. 
        ' Then call the FindStringExact method again, passing in the index of the
        ' current found item so the search starts there instead of 
        ' at the beginning of the list.
        While (resultIndex <> -1)
            count += 1
            resultIndex = ComboBox1.FindStringExact _
            (selectedEmployee, resultIndex)
        End While

        ' Update the text in Textbox1.
        TextBox1.Text = TextBox1.Text & Microsoft.VisualBasic.vbCrLf _
            & selectedEmployee & ": " & count
    End Sub

End Class

.NET Framework
Available since 1.1
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