What's the difference between code page and character encoding?

Question

My ASP.NET application imports CSV files. They are mostly saved in spreadsheet or notepad that asks for 'character set', for example: ISO-8859-2, Windows-1210, DOS-852 or Unicode(UTF-8).

Wiki says UTF-8 is a character encoding but Windows-1210 and ISO-8859-2 are code pages. Are these terms interchangeable?

.NET reads files saved in UTF-8 fine. Does it discover encoding itself?

Answer 1

Quotes from wiki:

"Code page is another name for character encoding. It consists of a table of values that describes the character set for a particular language."

http://en.wikipedia.org/wiki/Code_page

and:

"Windows code pages are sets of characters or code pages (known as character encodings in other operating systems) used in Microsoft Windows systems from the 1980s and 1990s."

Answer 2

You might want to check out Joel Spolsky's article and this post here

Answer 3

I think it is largely historic, but there is one clear distinction. A code page is a look-up table, one particular byte maps to a specific character. Different code pages use different mappings. In the olden days, those mappings weren't actually performed. Which required you to also have fonts that had glyphs to match the code page. Still a problem today btw, console windows have a code page.

There is no mapping in a Unicode encoding. They merely needs to squeeze 32-bits into an efficient format. Different Unicode encodings use different ways to squeeze the bits. The character always has a fixed value (codepoint in Unicode speak).

UTF encoded text files should have a BOM, allowing the reader to autodetect the encoding. No such convention exists for text files that were encoded with a code page. Getting good text out of them is a bit of a crap shoot. It's an evil that should die already :)

Answer 4

.NET classes such as StreamReader default to UTF-8 encoding; no it's not magically detected.