A.假设在C盘下建立一个123.txt文件,里面输入内容1234567890B.新建一个VB工程,在窗体上添加一个文本框,一个按钮以下是窗体代码:Const ReplacePosition = 5 '假设替换固定位置为5Private Sub Command1_Click() If IsNumeric(Text1.Text) = False Then MsgBox "请输入一个数字", vbExclamation + vbOKOnly, "警告" Exit Sub End If If Len(Text1.Text) > 1 Then MsgBox "输入的数字只能为一位数", vbExclamation + vbOKOnly, "警告" Exit Sub End If Dim b As Byte b = Asc(Text1.Text) Dim strFilePath As String strFilePath = "c:\123.txt" Open strFilePath For Random As #1 Len = 1 Put #1, ReplacePosition, b Close #1 MsgBox "修改成功", vbInformation + vbOKOnly, "信息"End SubPrivate Sub Form_Load() Text1.Text = ""End Sub