感觉NET的正则有BUG?

[liuyilin999]

正则表达式,多行模式
下面的代码应该有2次匹配末尾,但是只有一次??为什么??

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim matchesRegex As New Regex("ef$", RegexOptions.Multiline) '正则表达式
        Dim matchesFound As MatchCollection
        matchesFound = matchesRegex.Matches("ab123ef" + Chr(13) & Chr(10) + "ab234ef") '搜索所有匹配
        For Each match As Match In matchesFound
            MsgBox(match.Value)
        Next match
End Sub

^就没有问题能够正常匹配每行开头,2次

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim matchesRegex As New Regex("^ab", RegexOptions.Multiline) '正则表达式
        Dim matchesFound As MatchCollection
        matchesFound = matchesRegex.Matches("ab123ef" + Chr(13) & Chr(10) + "ab234ef") '搜索所有匹配
        For Each match As Match In matchesFound
            MsgBox(match.Value)
        Next match
End Sub

[兔子-顾问]

问题1
多行模式下，.可以捕获\n，但是不包含\r，因为原本就可以包含回车。
多行模式下，^表示行首，$表示行尾，但行尾的符号式\n，不是\r\n，文本框中是回车换行，你写的代码页是回车换行。那么第一行的ef后面就不是$，而是ef\r$。你可以试验下面的例子来验证

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim matchesRegex As New Regex("ef$", RegexOptions.Multiline) '正则表达式
        Dim matchesFound As MatchCollection
        matchesFound = matchesRegex.Matches("ab123ef" + vbLf + "ab234ef") '搜索所有匹配
        For Each match As Match In matchesFound
            MsgBox(match.Value)
        Next match
    End Sub

[兔子-顾问]

或是你可以看看你原本的，修改一下表达式，在$之前再匹配一个字符，就能捕获到2行了。
Dim matchesRegex As New Regex("ef.?$", RegexOptions.Multiline) '正则表达式
第一行的行尾有\r\n，第二行的行尾没有\r\n，则直接就是$，第一行的.会捕获到一个chr(13)

[xinv19shi]

不会！！！

[liuyilin999]

谢谢,但是为什么我如果从textbox1.text中取文本还是一次:
如textbox1.text中
abcdef
1234ef

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim matchesRegex As New Regex("ef$", RegexOptions.Multiline) '正则表达式
        Dim matchesFound As MatchCollection
        matchesFound = matchesRegex.Matches(TextBox1.Text) '搜索所有匹配
        For Each match As Match In matchesFound
            MsgBox(match.Value)
        Next match
    End Sub

[兔子-顾问]

看2楼回复，解释的很清楚了。正则换为
Dim matchesRegex As New Regex("ef.?$", RegexOptions.Multiline) '正则表达式
或是
Dim matchesRegex As New Regex("ef\r?$", RegexOptions.Multiline) '正则表达式

[liuyilin999]

结贴,谢谢wuyazhe