编vb根据半径求圆面积函数 用命令按钮事件过程调用之.用inputbox函数输入半径,将该值作为实参传入函数.

Const PI = 3.1416
'创建一个按钮Command1
Private Sub Command1_Click()
Dim a As Single
a = Val(InputBox("请输入半径大小！"))
MsgBox "半径为" & a & "的圆的面积是" & Format(area(a), "0.00")
End Sub

Private Function area(r As Single) As Single
area = PI * r * r
End Function