16.12. Reading or Writing Unicode Characters
print utf8_encode('Kurt Gödel is swell.');
print utf8_decode("Kurt G\xc3\xb6del is swell.");
There are 256 possible ASCII characters. The characters between codes 0 and 127 are standardized: control characters, letters and numbers, and punctuation. There are different rules, however, for the characters that codes 128-255 map to. One encoding is called ISO-8859-1, which includes characters necessary for writing most European languages, such as the ö in Gödel or the ñ in pestaña. Many languages, though, require more than 256 characters, and a character set that can express more than one language requires even more characters. This is where Unicode saves the day; its UTF-8 encoding can represent more than a million characters.
This increased functionality comes at the cost of space. ASCII characters are stored in just one byte; UTF-8 encoded characters need up to four bytes. Table 16-2 shows the byte representations of UTF-8 encoded characters.
Table 16-2. UTF-8 byte representation
In Table 16-2, the x positions represent bits used for actual character data. The least significant bit is the rightmost bit in the rightmost byte. In multibyte characters, the number of leading 1 bits in the leftmost byte is the same as the number of bytes in the character.
16.12.4. See Also
Documentation on utf8_encode( ) at http://www.php.net/utf8-encode and utf8_decode( ) at http://www.php.net/utf8-decode; more information on Unicode is available at the Unicode Consortium's home page, http://www.unicode.org; the UTF-8 and Unicode FAQ at http://www.cl.cam.ac.uk/~mgk25/unicode.html is also helpful.
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