How important is file encoding?

How import开发者_如何学JAVAant is file encoding? The default for Notepad++ is ANSI, but would it be better to use UTF-8 or what problems could occur if not using one or the other?

Yes, it would be better if everyone used UTF-8 for all documents always.

Unfortunately, they don't, primarily because Windows text editors (and many other Win tools) default to “ANSI”. This is a misleading name as it is nothing to do with ANSI X3.4 (aka ASCII) or any other ANSI standard, but in fact means the system default code page of the current Windows machine. That default code page can change between machines, or on the same machine, at which point all text files in “ANSI” that have non-ASCII characters like accented letters in will break.

So you should certainly create new files in UTF-8, but you will have to be aware that text files other people give you are likely to be in a motley collection of crappy country-specific code pages.

Microsoft's position has been that users who want Unicode support should use UTF-16LE files; it even, misleadingly, calls this encoding simply “Unicode” in save box encoding menus. MS took this approach because in the early days of Unicode it was believed that this would be the cleanest way of doing it. Since that time:

• Unicode was expanded beyond 16-bit code points, removing UTF-16's advantage of each code unit being a code point;

• UTF-8 was invented, with the advantage that as well as covering all of Unicode, it's backwards-compatible with 7-bit ASCII (which UTF-16 isn't as it's full of zero bytes) and for this reason it's also typically more compact.

Most of the rest of the world (Mac, Linux, the web in general) has, accordingly, already moved to UTF-8 as a standard encoding, eschewing UTF-16 for file storage or network purposes. Unfortunately Windows remains stuck with the archaic and useless selection of incompatible code pages it had back in the early Windows NT days. There is no sign of this changing in the near future.

If you're sharing files between systems that use differing default encodings, then a Unicode encoding is the way to go. If you don't plan on it, or use only the ASCII set of characters and aren't going to work with encodings that, for whatever reason, modify those (I can't think of any at the moment, but you never know...), you don't really need it.

As an aside, this is the sort of stuff that happens when you don't use a Unicode encoding for files with non-ASCII characters on a system with a different encoding from the one the file was created with: http://en.wikipedia.org/wiki/Mojibake

It is very importaint since your whatevertool will show false chars/whatever if you use the wrong encoding. Try to load a kyrillic file in Notepad without using UTF-8 or so and see a lot of "?" coming up. :)