|
|
Posted by Rik on 07/20/06 03:41
Bosconian wrote:
> "Rik" wrote:
>> Bosconian wrote:
>>> "Bosconian" wrote:
>>>> I need a regular expression to validate characters for a given file
>>>> name. I want to limit valid characters to the following:
>>>>
>>>> a-z
>>>> A-Z
>>>> 0-9
>>>> underscores
>>>> hyphens
>>>> white spaces
>>>>
>>>> The file name must end with a period and a 3-character extension.
>>>>
>>>> I also want to prevent repeat underscores, hyphens and white
>>>> spaces. Example: "__", "--" and " " would all be invalid.
>>>>
>>>> I found this example:
>>>>
>>>> ^[a-zA-Z0-9_\s-]+$
>>>>
>>>> This comes close, but it allows repeat underscores, hyphens and
>>>> white spaces. It also uses "\s" which allows carriage returns,
>>>> linefeeds, tabs, etc.
>>
>> I thought you wanted to allow whitespaces?
>>
>>>> Any help would be greatly appreciated.
>>> I almost have it:
>>>
>>> $pattern = "|[\wa-zA-Z0-9\-_]+\.[a-zA-Z0-9]{3}$|";
>> If you eant a WHOLE string to match, enchor it with both ^ and $
>>
>> /^([a-z0-9]+[\040_\-]?)*\.[a-z]{3}$/i
>>
>> Grtz,
> What about preventing a space before the period? For example:
> filename .txt
He didn't specify that, so I didn't bother. (allthough a consequence from my
regex is the name should start with somethning from [a-zA-z0-9], which he
didn't specify either).
80% of the work with regular expressions is figuring out what the exact
conditions are. If the regular expressions does what it's supposed to do,
but doesn'r behave like you'd expect, it clear you've got your
specifications wrong.
Offcourse, one could:
(1)
/^([\040_\-]?([a-z0-9]+)*\.[a-z]{3}$/i
(end with a character in [a-zA-Z0-9] before the dot.)
(2)
/^[a-z0-9]+([\040_\-]?([a-z0-9]+)*\.[a-z]{3}$/i
(begin & end with a character in [a-zA-Z0-9] before the dot.)
If we're _assuming_ it's a file_type validation, the '\.[a-z]{3}' isn't
valid either, lot's of filetypes have an extention shorter or longer then 3
characters, and not all int the range of {a-z]. (For instance mp3 or info)
Grtz,
--
Rik Wasmus
Navigation:
[Reply to this message]
|