windows程序设计 Unicode简介

An Introduction to Unicode

Very simply,Unicode is an extension of ASCII character encoding. Rather than the 7 bitsused to represent each character in strict ASCII, or the 8 bits per characterthat have become common on computers,
Unicode usesa full 16 bits for character encoding. This allows Unicode to represent all theletters, ideographs, and other symbols used in all the written languages of theworld that are likely to be used in computer communication.
Unicode is intendedinitially to supplement ASCII and, with any luck, eventually replace it. Consideringthat ASCII is one of the most dominant standards in computing, this iscertainly a tall order.

Unicodeimpacts every part of the computer industry, but perhaps most profoundlyoperating systems and programming languages. In this respect, we are almosthalfway there. Windows NT supports Unicode
from the ground up. (Unfortunately,Windows 98 includes only a small amount of Unicode support.) The C programming languageas formalized by ANSI inherently supports Unicode through its support of widecharacters, which I'll discuss in detail below.

Understandingthe difference between Unicode and DBCS is essential. Unicode is said to use(particularly in the context of the C programming language) "wide characters."Each
character in Unicode is 16 bits wide rather than 8 bits wide.Eight-bit values have no meaning inUnicode. In contrast, in a double-byte character set we're still dealing with8bit values. Some bytes define characters by themselves, and some bytesindicate
that another byte is necessary to completely define a character.