Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

When I try to save a file, if I use special characters in the name (such as a colon, question mark, or exclamation point) in Windows I get a message saying that the file name is invalid.

Why is that?

share|improve this question
2  
    
In which program are you trying to save a file, and is the offending character in the file or (as it seems) in the filename? –  Jukka K. Korpela Dec 27 '13 at 17:00
1  
add comment

1 Answer 1

There are several characters that have special meaning to Windows (and to DOS, where most of the characters originally came from)

from MSDN:

A filename cannot contain any of the following characters:
\ / : * ? " < > |

/ is a switch (and also a directory separator).
\ is a directory separator.
: is a drive designator.
* and ? are wildcards used in searching.
" is a way to allow spaces in parameters.
< and > are redirection that allow input and output of a program to come from, and go to, something other than screen/keyboard.
| is a pipe that allows output from one program to be used as input to the next

share|improve this answer
1  
To clarify this answer, these special characters could interfere with parsing a command line (or path) if they were in a filename. There is no requirement to delimit the filename in any way (e.g. surround it with quotes or spaces), so encountering such a special char would cause incorrect parsing (i.e is the special char part of the filename or an operator?). –  sawdust Dec 27 '13 at 20:41
    
It is, however, arguable that some of these restrictions are no longer necessary due to the handling of long filenames and quotations marks. \ ? * and " are the only ones really necessary in the current syntax, as the other characters are only useful outside of quotation marks. The exception is : which is only useful as the second character, which could be outlawed while allowing it elsewhere. In other words, no file named A:A letter's story.txt, but no problem with a file named Sarah: My favorite cat.txt –  trlkly Jun 5 at 23:41
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.