使用正则表达式测试文件名 [英] Test filename with regular expression

问题描述

我正在尝试使用此模式测试文件名字符串:

I am trying to test a filename string with this pattern:

^[A-Za-z0-9-_,\s]+[.]{1}[A-Za-z]{3}$

我想确保有一个三个字母的扩展名并允许字母、数字和以下符号: - _ 、 \s 在它之前，但我不想在文件名中包含所有字母和字符.我可以只使用 * 而不是 + 但这会匹配 0 或更多，这不是有效的文件名.

I want to ensure there is a three letter extension and allow letters, numbers and these symbols: - _ , \s to precede it but I don't want to have to include all of the letters and characters in the filename. I could just use a * instead of a + but that would match 0 or more which wouldn't be a valid filename.

以下是规则应如何反应的一些示例:

Here are some examples of how the rule should react:

Correct file name.pdf - true
Correct, file name.pdf - true
Correct_file_name.pdf - true
Correctfilename.pdf - true
Incorrect &% file name.pdf - false
Incorrect file name- false

如果有人能指出我正确的方向就好了.

It would be great if someone could point me in the right direction.

谢谢

推荐答案

您可以改用以下表达式:

You could use these expressions instead:

• \w - 与 [a-zA-Z0-9_]
相同
• \d - 与 [0-9]
相同
• \. - 与 [.]{1}
相同

• \w - is the same as [a-zA-Z0-9_]
• \d - is the same as [0-9]
• \. - is the same as [.]{1}

这将使您的正则表达式:

Which would make your regex:

^[\w,\s-]+\.[A-Za-z]{3}$

请注意，字符类中的文字破折号必须在第一个或最后一个或转义(我把它放在最后)，但是你把它放在中间，它错误地变成了一个范围.

Note that a literal dash in a character class must be first or last or escaped (I put it last), but you put it in the middle, which incorrectly becomes a range.

注意最后一个 [a-zA-Z] 不能被 \w 替换，因为 \w 包含下划线字符和数字.

Notice that the last [a-zA-Z] can not be replaced by \w because \w includes the underscore character and digits.

@tomasz 是对的！\w == [a-zA-Z0-9_](确认here)，所以我改变了我的答案，从第一个字符类中删除了不必要的 \d.

EDITED: @tomasz is right! \w == [a-zA-Z0-9_] (confirmed here), so I altered my answer to remove the unnecessary \d from the first character class.

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