mb_strwidth() returns width of string str.
Multi-byte character usually twice of width compare to single byte character.
表格 1. Characters width
| Chars | Width |
|---|---|
| U+0000 - U+0019 | 0 |
| U+0020 - U+1FFF | 1 |
| U+2000 - U+FF60 | 2 |
| U+FF61 - U+FF9F | 1 |
| U+FFA0 - | 2 |
encoding is character encoding. If it is omitted, internal encoding is used.
See also: mb_strimwidth(), mb_internal_encoding().