How to detect illegal characters in a string?

Question

Hi,

How to detect if there are any illegal characters in a string? In the input keyboard there are many characters that cant be used to create a filename eg characters like \ / : * ? " |. Besides these, there are quite a number of others.

So, how do I detect them?

Thanks

Answer 1

Easiest and most reliable way:  Try to create the file and see if it succeeds.

Harder, you can use something like strcspn (or its wide char brethren) to detect such illegal characters.

Answer 2

The variants available for strcspn are CString::FindOneOf and std::string::find_first_of.

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«_Superman_»
Microsoft MVP (Visual C++)

Polymorphism in C

Answer 3

you can also check with ASCII value for each char. If it is valid range, you can accept. otherwise, you can ignore the chars. 

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Thanks and Regards Selvam http://www15.brinkster.com/selvamselvam/

Answer 4

Thanks. Does someone know the ASCII range for all the illegal characters that can't be a part of a filename?

I tried searching on the web but couldn't find it yet.

Answer 5

\ / : * ? " < > |

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«_Superman_»
Microsoft MVP (Visual C++)

Polymorphism in C

Answer 6

You can use std::regex: "[(\\)(/)(:)(*)(?)(")(<)(>)(|)]". If this matches, you also have the capture groups so you can show a message with the invalid characters...