GetValidationSummary – Builds a validation summary for all the controls inside a container

' Return a validation summary string with all the error messages, if any,'  of the controls inside the specified container,'  associated to an ErrorProvider control' ' Example:'    Dim summary As String = ""'    ' display the validation summary for all the controls on the form'    summary = GetValidationSummary(Me, ErrorProvider1)'    If summary.Length > 0 Then'       MessageBox.Show(summary, "ERRORS", MessageBoxButtons.OK,'  MessageBoxIcon.Error)'    End If'    ' display the validation summary for all the controls inside a GroupBox'    summary = GetValidationSummary(GroupBox1, ErrorProvider1)'    If summary.Length > 0 Then'       MessageBox.Show(summary, "ERRORS", MessageBoxButtons.OK,'  MessageBoxIcon.Error)'    End IfFunction GetValidationSummary(ByVal container As Control, _    ByVal errorProv As ErrorProvider) As String    Return GetValidationSummary(container, errorProv, " - ")End FunctionFunction GetValidationSummary(ByVal container As Control, _    ByVal errorProv As ErrorProvider, ByVal prefix As String) As String    Dim summary As New System.Text.StringBuilder    Dim ctl As Control    ' for each control in the container (and its sub controls)...    For Each ctl In GetAllControls(container)        ' check the associated error message        Dim msg As String = errorProv.GetError(ctl)        ' if the error message is not null, add it to the summary        If msg.Length > 0 Then            If summary.Length > 0 Then                summary.Append(Environment.NewLine)            End If            summary.Append(prefix)            summary.Append(msg)        End If    Next    Return summary.ToString()End Function