(21) 在窗体上画一个命令按钮(其NAME属性为Command1),然后编写如下代码:
Option Base 1
Private Sub Command1_Click()
Dim a
s = 0
a = Array(1,2,3,4)
j = 1
For i = 4 To 1 Step -1
s = s + a(i) * j
j = j * 10
Next i
Print s
End Sub
运行上面的程序,单击命令按钮,其输出结果是
A) 4321 B) 1234 C) 34 D) 12
(22) 在窗体上画一个名称为Text1的文本框,要求文本框只能接收大写字母的输入。以下能实现该操作的事件过程是
A) Private Sub Text1_KeyPress(KeyAscii As Integer)
If KeyAscii < 65 Or KeyAscii > 90 Then
MsgBox "请输入大写字母"
KeyAscii = 0
End If
End Sub
B) Private Sub Text1_KeyDown(KeyCode As Integer, Shift As Integer)
If KeyCode < 65 Or KeyCode > 90 Then
MsgBox "请输入大写字母"
KeyCode = 0
End If
End Sub
C) Private Sub Text1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Asc(Text1.Text) < 65 Or Asc(Text1.Text) > 90 Then
MsgBox "请输入大写字母"
End If
End Sub
D) Private Sub Text1_Change()
If Asc(Text1.Text) > 64 And Asc(Text1.Text) < 91 Then
MsgBox "请输入大写字母"
End If
End Sub
(23) 假定在窗体(名称为Form1)的代码窗口中定义如下记录类型:
Private Type animal
AnimalName As String*20
AColor As String*10
End Type
在窗体上画一个名称为Command1的命令按钮,然后编写如下事件过程:
Private Sub Command1_Click()
Dim rec As animal
Open "c:\vbTest.dat" For Random As #1 Len = Len(rec)
rec.animalName = "Cat"
rec.aColor = "White"
Put #1, , rec
Close #1
End Sub
则以下叙述中正确的是
A) 记录类型animal不能在Form1中定义,必须在标准模块中定义
B) 如果文件c:\vbTest.dat不存在,则Open命令执行失败
C) 由于Put命令中没有指明记录号,因此每次都把记录写到文件的末尾
D) 语句“Put #1, , rec”将animal类型的两个数据元素写到文件中
(24) 在窗体上画一个名称为Text1的文本框,一个名称为Command1的命令按钮,然后编写如下事件过程和通用过程:
Private Sub Command1_Click()
n = Val(Text1.Text)
If n\2 = n/2 Then
f = f1(n)
Else
f = f2(n)
End If
Print f; n
End Sub
Public Function f1(ByRef x)
x=x*x
f1=x+x
End Function
Public Function f2(ByVal x)
x=x*x
f2=x+x+x
End Function