GB 18030 is a comprehensive character encoding standard used primarily in China to represent a wide range of characters, including Chinese characters, ASCII, and Unicode. Its encoding structure is variable-length, using 1, 2, or 4 bytes to encode characters.

GB 18030 uses different byte sequences to represent different types of characters:

• ASCII Characters (1 byte): Standard Latin characters, digits, punctuation, and control characters (0x00 to 0x7F).
• Extended GBK Characters (2 bytes): A character set for simplified and traditional Chinese characters as well as additional symbols and special characters, encoded in two-byte sequences where the first byte in range 0x81 to 0xFE and the second byte in 0x40 to 0x7E or 0x80 to 0xFE.
• Additional Unicode Characters (4 bytes): A character set to encode the vast number of characters introduced in Unicode versions beyond those covered by GBK, encoded in four-byte sequences where the first byte in range 0x81 to 0xFE, the second byte in range 0x30 to 0x39, the third byte in range 0x81 to 0xFE and the four byte in range 0x30 to 0x39.

This post is the fourth part in GB18030 Encoding and Decoding tutorial series. If you're interested in this topic, you can continue reading the next or previous part by using the following hyperlinks:

1. GB18030 Encoding and Decoding Part 1
2. GB18030 Encoding and Decoding Part 2
3. GB18030 Encoding and Decoding Part 3
4. GB18030 Encoding and Decoding Part 4
5. GB18030 Encoding and Decoding Part 5
6. GB18030 Encoding and Decoding Part 6
7. GB18030 Encoding and Decoding Part 7
8. GB18030 Encoding and Decoding Part 8
9. GB18030 Encoding and Decoding Part 9
10. GB18030 Encoding and Decoding Part 10

Additional Unicode Characters