byte- Модуль
- Строки →
- Получатель
- string
- Минимальное число аргументов
- 0
- Максимальное число аргументов
- 0
Declaration and parameters
Доступность
Включено по умолчанию · Да
These types are provided by the language. No module import is required.
The declarations below describe the standard operations on built-in values.
Получатель
string
Ограничения параметров
string. returns Option<int>. Index i counts Unicode scalars in the order of scalars(). It never counts UTF-8 bytes.
An index from zero to one less than the scalar count returns Some with the Unicode value of that scalar. A negative index or an index at or past the scalar count returns None(). The call does not fault for an index outside the text.
string. returns the number of bytes in the UTF-8 encoding of the stored scalars. Empty text returns 0. The count does not normalize text.
string. returns Array<string>. It scans the text from the start and divides it at each occurrence of sep that does not overlap an earlier occurrence.
The pieces keep source order. Adjacent separators and separators at either end produce empty pieces. Text without sep returns one piece that holds the whole text. Empty text returns one empty piece. Joining the pieces with sep reproduces the text.
An empty separator faults at run time with TPZ5001 at the call. Divide text into Unicode scalars with scalars() or into grapheme clusters with graphemes().
Результат
The declared result type is int.
Эффекты
Ошибки
Result and effects
Count the UTF-8 bytes of the stored scalars without normalization. Empty text returns 0.
Related entries
Read code points, byte counts and separated pieces
Read code points, byte counts and separated pieces
string. returns Option<int>. Index i counts Unicode scalars in the order of scalars(). It never counts UTF-8 bytes.
An index from zero to one less than the scalar count returns Some with the Unicode value of that scalar. A negative index or an index at or past the scalar count returns None(). The call does not fault for an index outside the text.
string. returns the number of bytes in the UTF-8 encoding of the stored scalars. Empty text returns 0. The count does not normalize text.
string. returns Array<string>. It scans the text from the start and divides it at each occurrence of sep that does not overlap an earlier occurrence.
The pieces keep source order. Adjacent separators and separators at either end produce empty pieces. Text without sep returns one piece that holds the whole text. Empty text returns one empty piece. Joining the pieces with sep reproduces the text.
An empty separator faults at run time with TPZ5001 at the call. Divide text into Unicode scalars with scalars() or into grapheme clusters with graphemes().
Причина
Text algorithms name their unit. code uses the scalar unit of scalars() and reports absence as a value, so a classifier can read the first scalar of any text without a separate length test. byte gives the UTF-8 size that wire formats and byte limits use. split divides text at literal separator text, while Regex. divides it at a pattern. An empty separator marks no position, so the call faults and the program chooses a text unit explicitly.
Read scalar values by scalar index
import std.iofunction show(value: Option<int>) -> string {match (value) {case Some(point) => "{point}"case None() => "none"}}let text = "a가😀"for index in ([-1, 0, 1, 2, 3]) {io.writeLine("{index}: {show(text.codePointAt(index))}")}
-1: none
0: 97
1: 44032
2: 128512
3: none
Ожидаемый результат
Ожидаемый результат
Выполнение завершается. Код завершения 0.
-1: none0: 971: 440322: 1285123: none
Compare scalar counts with UTF-8 byte counts
import std.iofor text in (["", "a", "가", "😀", "a가😀"]) {io.writeLine("{text.scalars().length} {text.byteLength()}")}
0 0
1 1
1 3
1 4
3 8
Ожидаемый результат
Ожидаемый результат
Выполнение завершается. Код завершения 0.
0 01 11 31 43 8
Keep empty pieces between separators
import std.iofunction show(pieces: Array<string>) -> string {"{pieces.length} [{pieces.join("|")}]"}io.writeLine(show("a,b,,c,".split(",")))io.writeLine(show("a::b".split("::")))io.writeLine(show("aaa".split("aa")))io.writeLine(show("plain".split(",")))io.writeLine(show("".split(",")))let text = ",x,"io.writeLine("{text.split(",").join(",") == text}")
5 [a|b||c|]
2 [a|b]
2 [|a]
1 [plain]
1 []
true
Ожидаемый результат
Ожидаемый результат
Выполнение завершается. Код завершения 0.
5 [a|b||c|]2 [a|b]2 [|a]1 [plain]1 []true
Fault on an empty separator
import std.iolet separator = ""let _ = "abc".split(separator)io.writeLine("after")
Нет стандартного вывода.Ожидаемый результат
Ожидаемый результат
Этап отклонения run. Ненулевой код завершения.
stdlib-string-split-empty-separator at
main.tpz:4:9