本程序中，定义了objPrintDocument为一个打印类。然后调用PrintDialog的AllowPrintToFile属性，是否启用打印到文件。然后用了If...Else...End If语句，如果TextBox5的内容不为空的话又执行一个If...Then...End If语句，如果用户点击了打印的确定按钮，则执行一个Try...Catch语句。Try语句里面定义PrintDoc为PrintDocument类，然后连接事件PrintDoc.PrintPage，并引用过程PrintText。接着调用PrintDocument的Print方法。Catch语句里面弹出对话框显示"sorry"。
此软件的打印部分程序如下:
     Private Sub ToolStripButton2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs)      Handles ToolStripButton2.Click
         Dim objPrintDocument As PrintDocument = New PrintDocument()
         objPrintDocument.DocumentName = "Text File Print "
         PrintDialog1.AllowPrintToFile = False
         PrintDialog1.AllowSelection = False
         PrintDialog1.AllowSomePages = False
         PrintDialog1.Document = objPrintDocument
         If TextBox5.Text <> Nothing Then
             If PrintDialog1.ShowDialog() = Windows.Forms.DialogResult.OK Then
                 Try
                     Dim PrintDoc As PrintDocument = New PrintDocument()
                     AddHandler PrintDoc.PrintPage, AddressOf Me.PrintText
                     PrintDoc.Print()
                  Catch ex As Exception
                      MessageBox.Show("sorry", ex.ToString)
                  End Try
              End If
          Else
              MsgBox("Please open a file frist! ", MsgBoxStyle.OkOnly)
          End If
     End Sub
     通用过程PrintText里面用到了两个If...Then...End If语句。第一个If...Else...End If语句,如果TextBox5不为空，则调用Split函数拆分字符串并赋值给前面定义的字符串数组MyArr。若TextBox5为空，则弹出对话框提示请打开一个文件。在第二个If...Then...End If语句里面，如果字符串数组MyArr的长度大于0，则执行有限循环For...Next语句。在For...Next语句里面设置了打印界面的宽度尺寸。然后调用了Graphics的DrawString方法，在指定的位置用指定的文本格式绘制指定的文本字符串。接着设置了绘图对象的HasMorePages属性，设为False，只打印一页。
     Private Sub PrintText(ByVal sender As Object, ByVal ev As PrintPageEventArgs)
          Dim sngTopMargin As Single = ev.MarginBounds.Top
          Dim widthOfprint As Integer 基于VB.NET的辐射报警仪上位机管理软件设计(15):http://www.751com.cn/tongxin/lunwen_2658.html