This was relevant years ago. The others are control characters such as carriage return, line feed , tab, etc. Because the center of the computer industry was in the USA at that time. As Tom pointed out in his comment below there is no such thing as " extended ASCII " yet this is an easy way to refer to this 8th-bit trick. Chinese and the likes? We would have needed an entirely new character set Unicode doesn't contain every character from every language, but it sure contains a gigantic amount of characters see this table.
You cannot save text to your hard drive as "Unicode". Unicode is an abstract representation of the text. You need to "encode" this abstract representation. That's where an encoding comes into play.
This answer does a pretty good job at explaining the basics:. This is obvious for some, but just in case. We have seven slots available filled with either 0 or 1 Binary Code. Each can have two combinations. Think about this as a combination lock with seven wheels, each wheel having two numbers only.
Source: Wikipedia , this great blog post and Mocki. ASCII has code points, 0 through It can fit in a single 8-bit byte, the values through tended to be used for other characters. With incompatible choices, causing the code page disaster. Text encoded in one code page cannot be read correctly by a program that assumes or guessed at another code page. Unicode came about to solve this disaster.
Version 1 started out with code points, commonly encoded in 16 bits. Later extended in version 2 to 1. The current version is 6. That doesn't fit in 16 bits anymore. Encoding in bits was common when v2 came around, used by Microsoft and Apple operating systems for example.
And language runtimes like Java. The v2 spec came up with a way to map those 1. An encoding called UTF, a variable length encoding where one code point can take either 2 or 4 bytes.
The original v1 code points take 2 bytes, added ones take 4. The only non-variable length encoding is UTF, takes 4 bytes for a code point. Not often used since it is pretty wasteful. Having these different encoding choices brings back the code page disaster to some degree, along with heated debates among programmers which UTF choice is "best". Their association with operating system defaults pretty much draws the lines.
It indicates both the UTF encoding and the endianess and is neutral to a text rendering engine. Unfortunately it is optional and many programmers claim their right to omit it so accidents are still pretty common.
Hence the size of char in java is 2 bytes. And range is 0 to ASCII has code positions, allocated to graphic characters and control characters control codes. Unicode has 1,, code positions. About , of them have currently been allocated to characters, and many code points have been made permanently noncharacters i.
Sometimes, however, Unicode is characterized even in the Unicode standard! This is a slogan that mainly tries to convey the idea that Unicode is meant to be a universal character code the same way as ASCII once was though the character repertoire of ASCII was hopelessly insufficient for universal use , as opposite to using different codes in different systems and applications and for different languages.
These code numbers can be presented using different transfer encodings, and internally, in memory, Unicode characters are usually represented using one or two bit quantities per character, depending on character range, sometimes using one bit quantity per character.
Basically, they are standards on how to represent difference characters in binary so that they can be written, stored, transmitted, and read in digital media. The main difference between the two is in the way they encode the character and the number of bits that they use for each. ASCII originally used seven bits to encode each character. In contrast, Unicode uses a variable bit encoding program where you can choose between 32, 16, and 8-bit encodings.
Unicode virtually eliminates this problem as all the character code points were standardized. Another major advantage of Unicode is that at its maximum it can accommodate a huge number of characters.
Because of this, Unicode currently contains most written languages and still has room for even more. This includes typical left-to-right scripts like English and even right-to-left scripts like Arabic. Chinese, Japanese, and the many other variants are also represented within Unicode.
In order to maintain compatibility with the older ASCII, which was already in widespread use at the time, Unicode was designed in such a way that the first eight bits matched that of the most popular ASCII page. This facilitated the adoption of Unicode as it lessened the impact of adopting a new encoding standard for those who were already using ASCII. Cite APA 7 , l. Difference Between Similar Terms and Objects.
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