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:ref:`sub <utf8-sub>`
Substrings
:ref:`len <utf8-len>`
Length in characters
:ref:`next <utf8-next>`
Character-at-a-time iterations
Parameters
a string encoded with UTF-8
return
-1 meaning "less", 0 meaning "equal", +1 meaning "greater"
rtype
number
Compare two strings with the Default Unicode Collation Element Table (DUCET) for the `Unicode Collation Algorithm <http://www.unicode.org/Public/UCA/10.0.0/allkeys.txt>`_. Thus 'å' is less than 'B', even though the code-point value of å (229) is greater than the code-point value of B (66), because the algorithm depends on the values in the Collation Element Table, not the code-point values.
The comparison is done with primary weights. Therefore the elements which affect secondary or later weights (such as "case" in Latin or Cyrillic alphabets, or "kana differentiation" in Japanese) are ignored. If asked "is this like a Microsoft case-insensitive accent-insensitive collation" we tend to answer "yes", though the Unicode Collation Algorithm is far more sophisticated than those terms imply.
**Example:**
tarantool> utf8.casecmp('é','e'),utf8.casecmp('E','e')
---
- 0
- 0
...
a Unicode code point value, repeatable
a UTF-8 string
string
The code-point number is the value that corresponds to a character in the `Unicode Character Database <http://www.unicode.org/Public/5.2.0/ucd/UnicodeData.txt>`_ This is not the same as the byte values of the encoded character, because the UTF-8 encoding scheme is more complex than a simple copy of the code-point number.
Another way to construct a string with Unicode characters is with the \\u{hex-digits} escape mechanism, for example '\\u{41}\\u{42}' and ``utf8.char(65,66)`` both produce the string 'AB'.
tarantool> utf8.char(229)
---
- å
...
Compare two strings with the Default Unicode Collation Element Table (DUCET) for the `Unicode Collation Algorithm <http://www.unicode.org/Public/UCA/10.0.0/allkeys.txt>`_. Thus 'å' is less than 'B', even though the code-point value of å (229) is greater than the code-point value of B (66), because the algorithm depends on the values in the Collation Element Table, not the code values.
The comparison is done with at least three weights. Therefore the elements which affect secondary or later weights (such as "case" in Latin or Cyrillic alphabets, or "kana differentiation" in Japanese) are not ignored. and upper case comes after lower case.
tarantool> utf8.cmp('é','e'),utf8.cmp('E','e')
---
- 1
- 1
...
a single UTF8 character, expressed as a one-byte string or a code point value
true or false
boolean
Return true if the input character is an "alphabetic-like" character, otherwise return false. Generally speaking a character will be considered alphabetic-like provided it is typically used within a word, as opposed to a digit or punctuation. It does not have to be a character in an alphabet.
tarantool> utf8.isalpha('Ж'),utf8.isalpha('å'),utf8.isalpha('9')
---
- true
- true
- false
...
Return true if the input character is a digit, otherwise return false.

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testing_project / Documentation: reference/reference_lua/utf8 — English

tarantool> utf8.casecmp('é','e'),utf8.casecmp('E','e')
---
- 0
- 0
...
2 years ago
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string 27