If TextBox3.Text <> "*" Or TextBox3.Text <> "/" Or TextBox3.Text <> "+" Or TextBox3.Text <> "-" Then MsgBox("请在第三个框中输入运算符!") TextBox3.Text = "" TextBox3.Focus()
If TextBox3.Text <> "*" Or TextBox3.Text <> "/" Or TextBox3.Text <> "+" Or TextBox3.Text <> "-" Then MsgBox("请在第三个框中输入运算符!") TextBox3.Text = "" TextBox3.Focus()