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2010-12-06, 22:04:21
Hi,
UTF-8 is a multi-bytes encoding (and variable-width encoding), using one (ASCII) to three (Hindi) bytes according to character nature. UTF-16 follow the same process but use more space for ASCII and less for non-ASCII.
substr() is a byte substraction function : when you set start and stop, you are not indicating characters but bytes. If the encoding use single bytes (like ASCII) it's the same thing, but if the encoding use multi-bytes (UTF-x, ISO-x...), you could cut a string in the middle of a character bytes, who become unreadable. To avoid this, you have to know the number of bytes used by every characters : it's the work of mb_substr().
mb_substr() is a multi-bytes (and variable-width) substraction function : when you set start and stop, you are indicating characters, according to a specific encoding. The function manage the number of bytes to skip according to every character bytes width.
To read :
http://en.wikipedia.org/wiki/UTF-8
http://en.wikipedia.org/wiki/UTF-8#Description
http://en.wikipedia.org/wiki/UTF-8#Disadvantages_2
http://en.wikipedia.org/wiki/Character_encoding
http://en.wikipedia.org/wiki/Variable-width_encoding
http://php.net/manual/en/ref.mbstring.php
http://php.net/manual/en/function.substr.php
http://php.net/manual/en/function.mb-substr.php
UTF-8 is a multi-bytes encoding (and variable-width encoding), using one (ASCII) to three (Hindi) bytes according to character nature. UTF-16 follow the same process but use more space for ASCII and less for non-ASCII.
substr() is a byte substraction function : when you set start and stop, you are not indicating characters but bytes. If the encoding use single bytes (like ASCII) it's the same thing, but if the encoding use multi-bytes (UTF-x, ISO-x...), you could cut a string in the middle of a character bytes, who become unreadable. To avoid this, you have to know the number of bytes used by every characters : it's the work of mb_substr().
mb_substr() is a multi-bytes (and variable-width) substraction function : when you set start and stop, you are indicating characters, according to a specific encoding. The function manage the number of bytes to skip according to every character bytes width.
To read :
http://en.wikipedia.org/wiki/UTF-8
http://en.wikipedia.org/wiki/UTF-8#Description
http://en.wikipedia.org/wiki/UTF-8#Disadvantages_2
http://en.wikipedia.org/wiki/Character_encoding
http://en.wikipedia.org/wiki/Variable-width_encoding
http://php.net/manual/en/ref.mbstring.php
http://php.net/manual/en/function.substr.php
http://php.net/manual/en/function.mb-substr.php
yojoe Wrote:edit: completely forgot to mention about changes you made. I'm glad you didn't at least delete whole credits xDOh, I hope not to have done something wrong! I worked on it after your request for help, and could not hold me to restructure the whole. The official author, indicated in the admin panel is still you :\
