Clear Unicode character encoding 8- [4] (utf-8)

This blog describes actually stored in Unicode encodingutf-8

What is utf-8

• utf-8Storing encoded is a practical
• That is, it can be stored coding theory ucs2and coding theory can be storeducs4
• Storing variable length, the length of each character encoding may not be the same.
• It is to solve ucs-2waste problems arising.

How utf-8 storage ucs2

Program

range	Program
$0 < x \leq 7$	0xxxxxxx
$7 < x \leq 11$	110xxxxx 10xxxxxx
$11 < x \leq 16$	1110xxxx 10xxxxxx 10xxxxxx
$16 < x \leq 21$	11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
$21 < x \leq 26$	111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
$26 < x \leq 31$	1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx

Encoding step

• Step One: Find the original ucs-2coding
  • For example, 经the word is encoded ucs-201111110 11001111
• Step two: in bytes high last year0
  • After the removal of the high 0, encoded into a word 1111110 11001111, leaving 15
• The third step: the rest of the digits seen x, look for the corresponding program based on the remaining digits
  • Here we should find solutions1110xxxx 10xxxxxx 10xxxxxx
• Step 4: According to "the order from right to left" to fill the remaining coding scheme of xthe
  • Here, to 1111110 11001111fill to 1110xxxx 10xxxxxx 10xxxxxxthe
  • The results should be filled: 1110X 111 10 111011 10 001111
• Step 5: if x is filled with zeros to fill the rest of the well, to give utf-8 encoded
  • 1110x111 10111011 10001111X obtained after the filling with 011100111 10111011 10001111
  • So characters 经of utf-8 encoding is11100111 10111011 10001111

How utf-8 storage ucs4

• Like the storage ucs2, but also longer storage.

• But when encoding ucs2only use the first three kinds of programs, ucs4six kinds of programs used in plenary.