Aaron W. LaFramboise wrote:
David Abrahams wrote:
"Tony Juricic" <tonygeek@yahoo.com> writes:
Even MS IDE has problems in some cases (very inconsistent) when space characters are present but I thought that in most Wintel and also UNIX command tools these issues are easily solved with adding quotes?
You'd be surprised how much complication that adds for some people.
I'd just like to point out that in the command-line Windows world, spaces in a single argument of any kind, including filenames, are doomed to fail eventually, because native Windows command lines are simply a single linear string of characters. There is no array of strings as in Unix, no matter what argv says. There is also no particular standard or agreement on how one might group arguments or indicate that several whitespace-delimited tokens should b considered as one, although various quote characters sometimes work.
There is a standard which is implemented by CommandLineToArgvW (Windows NT only) and by MSVCRT. This is: - spaces are treated as literal and not as argument separators if they appear between consecutive non-literal double-quotes - double-quotes are treated as literal if they are prefixed by an odd number of backslashes - backslashes are generally treated as literal, but in a sequence of backslashes immediately preceding a double-quote only every second backslash is literal So when generating a command-line you can do something like: string argv_to_line(const vector<string> & argv) { string line; for (vector<string>::const_iterator it = argv.begin(), end = argv.end(); it != end; ++it) { if (!it->empty() && it->find_first_of(" \"") == string::npos) line.append(*it); else { line.append(1, '"'); size_t backslashes = 0; for (size_t i = 0; i != it->size(); ++i) if ((*it)[i] == '\\') ++backslashes; else if ((*it)[i] == '"') { line.append(backslashes * 2 + 1, '\\'); line.append(1, '"'); backslashes = 0; } else { if (backslashes) line.append(backslashes, '\\'); line.append(1, (*it)[i]); backslashes = 0; } if (backslashes) line.append(backslashes * 2, '\\'); line.append(1, '"'); } line.append(1, ' '); } return line; } Examples: Unquoted Quoted -------------------------- abc def "abc def" abc \def "abc \def" abc def" "abc def\"" abc def\ "abc def\\" abc def\" "abc def\\\"" abc\\ def "abc\\ def" abc def\\ "abc def\\\\"
Writers of command line programs can work around this on a case-by-case basis, such as adopting the convention to use the double-quote as a grouping character. However, in nontrivial systems where command line programs are passing data to other command line programs, it is the usual case that some component or other inappropriately quotes for a subprogram, or forgets to quote filenames at all.
Yes, this is true. In fact the same goes for Unix if there are any shell scripts involved, since variables with spaces in magically split themselves into multiple arguments if you forget to quote them.
For this reason, spaces should never be used in filenames of projects intended to be robust on Windows. On the other hand, writers of command line programs that accept filenames as a parameter should always test their programs to ensure that filenames with spaces will be accepted correctly.
I would have thought that was the responsibility of those writing startup code. Ben.