Return width of string (PHP 4 >= 4.0.6, PHP 5)
int mb_strwidth ( string str [, string encoding] )

mb_strwidth() returns width of string str.

Multi-byte character usually twice of width compare to single byte character.

表 151. Characters width

U+0000 - U+00190
U+0020 - U+1FFF1
U+2000 - U+FF602
U+FF61 - U+FF9F1
U+FFA0 - 2

encoding is character encoding. If it is omitted, internal encoding is used.

See also: mb_strimwidth(), mb_internal_encoding().