Beman Dawes wrote:

"Paul Giaccone" wrote in message news:43EC8417.8010000@cinesite.co.uk...

...

The following line in my Windows program:

boost::filesystem::path my_path(my_filename, boost::filesystem::native);

converts backslashes in my_filename to forward slashes, which means than when I use boost::filesystem::exists on the result, the file is reported as not existing even though it does.

I notice the comments in boost::filesystem::m_path_append(), which is called by the constructor of boost::filesystem::path, say that this is what the function does, but this contradicts the documentation. http://boost.org/libs/filesystem/doc/portability_guide.htm says, of native:

Side effect: Syntax for path constructor /src/ string is implementation defined according to the path syntax rules for the operating system.

Use: In path constructors, when the source is operator input or other sources which are formatted according to operating system rules.

I understand this to mean that boost::filesystem::native converts the file into the format required by the OS. I certainly would not expect it to make the format wrong if it is already correct.

Is there something I've overlooked here, or is this a bug, or is the documentation wrong (or just misleading)? I'm puzzled.

I assume you are using 1.33.1 or earlier. It certainly handles both back and forward slashes correctly for the mostpart, although I wouldn't be surprised if there were obsure bugs in corner cases such as \\? pathnames.

Why don't you give the 1.34 version from the CVS HEAD a try. It uses a much simplified (and hopefully improved) way of handling native formats. You no longer have to do anything special such as using a special constructor argument.

Good luck,

--Beman

Thanks. I was about to post an example of what I am doing, but, bizarrely, it's all working now. The boost::filesystem::path is initialised from a std::string of the form <drive>:\<dir1>\<dir2>\....\<dirn>/<filename>.<extension> and the backslashes is converted to forward slashes. The .string() function (and the .c_str() function on that) give strings containing forward slashes. ::exists() says the file exists, and the file loads OK. I'm using Windows Visual C++ 7.1.3088 and Boost 1.33.1. I wonder what was wrong before. The problem just seems to have gone away of its own accord. I did not recompile the program or change the input. Still, it's back to the correct behaviour, so I'm not complaining. Thanks for your feedback in any case. Paul