Question

一道vb的题目 我真不知道keypress怎么捕获回车

此程序目的是判断一个数是否是回文（例如12321，1221为回文）

Dim s As Integer
Private Sub Text1_KeyPres(KeyAscii As Integer)
If KeyAscii = 13 Then
s = Val(Text1.Text)
If Ishw(s) Then
List1.AddItem s & " 不是回文"
Else: List1.AddItem s & " 是回文"
End If
End If
End Sub

Private Function Ishw(ByVal n As Integer) As Integer
Dim a() As Integer
Dim sum As Integer
Dim i As Integer
Ishw = 0
i = Len(t)
For i = 1 To s
a(i) = Mid(s, i, i)
Next i
For i = 1 To s / 2
If a(i) <> a(s - i + 1) Then
Ishw = 1
Exit For
End If
Next i
End Function

Answer 1

很多错误，修改如下：

Private Sub Text1_KeyPress(KeyAscii As Integer)  '注意事件名称，不要写错
Dim s As Integer '不需要定义为全局变量
If KeyAscii = 13 Then
    s = Val(Text1.Text)
    If Ishw(s) Then
        List1.AddItem s & "    不是回文"
    Else
        List1.AddItem s & "    是回文"
    End If
End If
End Sub
Private Function Ishw(ByVal n As Integer) As Boolean '返回值定义为逻辑型
Dim i As Integer
Ishw = True
For i = 1 To Len(CStr(n)) \ 2
    If Mid(CStr(n), i, 1) = Mid(CStr(n), Len(CStr(n)) - i + 1, 1) Then
        Ishw = False
        Exit For
    End If
Next i
End Function

Answer 2

第三行If KeyAscii = 13 Then这句，表示如果按下的按键的ASCII编码为13，即为Enter键，则执行。

Answer 3

要把form的KeyPreview设置成true，才能捕获控件的KeyPress事件。

Answer 4

keypress事件不行捕获回车键，就用 keyDown事件，用keycode = 13 判断

Answer 5

Text1_KeyPres

改为
Text1_KeyPress