How to validate french chars? (Base on external file name)

Can anybody advise that how to validate french chars? (chars Base on external file name)
An example would be appreciated!

What do you mean by "validate"? What would the inputs of this validation be, and what the outputs?

Actually, my purpose is to validate file name with allowing only English(a-Z), underscore “_”, dot “.” , French chars(a-Z, is it?) and numeric char(0-9).

Thanks

So the question is "What characters can appear in French words", is it?

the question is how to check if the file name only contain English character, underscore “_”, dot “.” , French characters, and numeric char(0-9).

A simple example is appreciated!

I see, so you know the list of characters you want to accept. In that case a simple regex which only accepts those characters might be the best way to do this.

(I don't know why you would want to apply such a limitation to the file name, but that's a separate question.)

Paul Clapham wrote:I see, so you know the list of characters you want to accept. In that case a simple regex which only accepts those characters might be the best way to do this.

(I don't know why you would want to apply such a limitation to the file name, but that's a separate question.)

What exactly do I need to do?
Do I need to collect all valid chars then check if every input match one in collection?

I don't understand the question. Are you saying that you don't know how to use a regex, or that you don't know how to write a regex for this particular problem, or that you want to use something else instead, or what?

Paul Clapham wrote:I don't understand the question. Are you saying that you don't know how to use a regex, or that you don't know how to write a regex for this particular problem, or that you want to use something else instead, or what?

I know how to deal with numeric and English chars in Regex(just input A-Z, 0-9, into my expression pattern), how about those french characters?

You just put them in too. Or did you try it and have a problem? If so, posting details about the problem would be helpful.