Question

输入半径，用VB编写计算圆面积和圆周长的程序

为保证程序运行的正确，对输入的半径进行合法检查，数据检查调用ISNUMERIC函数，利用MSGBOX先是出错信息，结果保留两位小数。要求面积和周长用两个COMMAND完成。半径用一个标签控制输入。谢谢。

Answer 1

Private Sub Label2_Click()
const PI = 3.14159
Dim r As Single, i As Single, s As Single
r = InputBox("请输入半径:", "输入半径")
i = 2 * PI * r
s = PI * r ^ 2
Label2 = Label2 & r
Label3 = Label3 + Str(i)
Label4 = Label4 + Str(s)
End Sub

当然你要有四个Label控件，第一个可以随便设置，例如写成“计算圆的周长与面积”

Answer 2

Private Sub Command1_Click()
Dim bj As Single
Dim zz As Single
Dim mj As Single
bj = CSng(Text1.Text)
If bj <= 0 Then
MsgBox "你的输入有误"
Exit Sub
End If
mj = 3.1415 * bj * bj
MsgBox "面积是" & Format(mj, "0.00")

End Sub

Private Sub Command2_Click()
Dim bj As Single
Dim zz As Single
Dim mj As Single
bj = CSng(Text1.Text)
If bj <= 0 Then
MsgBox "你的输入有误"
Exit Sub
End If
zz = 2 * bj * 3.1415
MsgBox "周长是" & Format(zz, "0.00")
End Sub