Question

vb编程时出现无效外部过程，怎么办/

Dim radius As Single, length As Double, area As Double
radius = Text1.Text
length = 2 * 3.14159 * radius
area = 3.14159 * radius * radius
Text2.Caption = length
Text3.Caption = area
End Sub
Private Sub Com()
mand1_Click()
End Sub
Private Sub Command1_Click()
End Sub
Private Sub Form_Load()
End Sub

Answer 1

执行到哪一行出现错误了？你贴出来的代码很混乱。

首先是这一段：
Private Sub Com()
mand1_Click()
End Sub
明显应该是：
Private Sub Command1_Click()
End Sub
但是这个过程下面已经有了，重复了。

其次最开始的那几行代码，前面应该是有一个对应的Private Sub的，我不知道是你没粘贴出来还是压根没有。

Answer 2

把你的代码全删掉，换成这个：
Private Sub Command1_Click()
Dim radius As Single, length As Double, area As Double
radius = Text1.Text
length = 2 * 3.14159 * radius
area = 3.14159 * radius * radius
Text2.Text = length
Text3.Text = area
End Sub