The Insert() function in String Class will insert a String in a specified index in the String instance.

System.String.Insert(Integer ind, String str) as String

Parameters:

ind - The index of the specified string to be inserted.

str - The string to be inserted.

Returns:

String - The result string.

Exceptions:

System.ArgumentOutOfRangeException: startIndex is negative or greater than the length of this instance

System.ArgumentNullException : If the argument is null.

For ex:

"This is Test".Insert(8,"Insert ") returns "This is Insert Test"

Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, _
    ByVal e As System.EventArgs) Handles Button1.Click
        Dim str As String = "This is VB.NET Test"
        Dim insStr As String = "Insert "
        Dim strRes As String = str.Insert(15, insStr)
        MsgBox(strRes)
    End Sub
End Class