代码如下。

＝＝＝＝＝＝＝＝＝＝＝＝＝＝ Private Sub Form_Load() Do Dim a As Single, b As Single, c As Single, p As Single, s As Single a = Val(InputBox("请输入三角形第1条边长")) If a = -1 Then Exit Do b = Val(InputBox("请输入三角形第2条边长")) If b = -1 Then Exit Do c = Val(InputBox("请输入三角形第3条边长")) If c = -1 Then Exit Do p = (a + b + c) / 2 If a >= p Or b >= p Or c >= p Then MsgBox "不能构成三角形" Else s = Sqr(p * (p - a) * (p - b) * (p - c)) MsgBox "面积为" & s End If Loop End End Sub。