Special Characters in sharepoint 2010 file/folder name?

Question

What special characters are allowed and not allowed in sharepoint file/folder names?

Answer 1

The rules are "very simple" (see the full KB article here), which is why you should alway use SPUrlUtility to check filenames.

Except about folders and files:

Folder names
•You cannot use the following characters anywhere in a folder name or a server name:
◦tilde
◦number sign
◦percent ◦ampersand
◦asterisk
◦braces
◦backslash
◦colon
◦angle brackets
◦question mark
◦slash
◦pipe
◦quotation mark
•You cannot use the period character consecutively in the middle of a folder name.
•You cannot use the period character at the end of a folder name.
•You cannot start a folder name with the period character.

File names
•You cannot use the following characters anywhere in a file name:
◦tilde
◦number sign
◦percent
◦ampersand
◦asterisk
◦braces
◦backslash
◦colon
◦angle brackets
◦question mark
◦slash
◦pipe
◦quotation mark
•You cannot use the period character consecutively in the middle of a file name.
•You cannot use the period character at the end of a file name.
•You cannot start a file name with the period character.
•In addition, file names and folder names may not end with:
◦.files
◦_files
◦-Dateien
◦_fichiers
◦_bestanden
◦_file
◦_archivos
◦-filer
◦ _tiedostot
◦_pliki
◦_soubory
◦_elemei
◦_ficheiros
◦_arquivos
◦_dosyalar
◦_datoteke
◦_fitxers
◦ _failid
◦_fails
◦_bylos
◦_fajlovi
◦ _fitxategiak

Answer 2

You should call SPEncode.UrlEncode, passing in filename.