langref: add paragraph and examples about indexing non-ASCII strings

PR #10610 addressed most of the points from #1854.  This
additional paragraph and examples covers the OMISSIONS section
clarifying issues about indexing into non-ASCII strings (whether valid
UTF-8 or not).  I think this finally closes #1854.
This commit is contained in:
Josh Holland 2023-01-27 18:29:28 +00:00 committed by Veikka Tuominen
parent 86ec26b1f0
commit 1fba88450d

View file

@ -871,6 +871,13 @@ pub fn main() void {
However, it is possible to embed non-UTF-8 bytes into a string literal using <code>\xNN</code> notation.
</p>
<p>
Indexing into a string containing non-ASCII bytes will return individual bytes, whether valid
UTF-8 or not.
The {#link|Zig Standard Library#} provides routines for checking the validity of UTF-8 encoded
strings, accessing their code points and other encoding/decoding related tasks in
{#syntax#}std.unicode{#endsyntax#}.
</p>
<p>
Unicode code point literals have type {#syntax#}comptime_int{#endsyntax#}, the same as
{#link|Integer Literals#}. All {#link|Escape Sequences#} are valid in both string literals
and Unicode code point literals.
@ -894,9 +901,12 @@ pub fn main() void {
print("{}\n", .{'e' == '\x65'}); // true
print("{d}\n", .{'\u{1f4a9}'}); // 128169
print("{d}\n", .{'💯'}); // 128175
print("{}\n", .{mem.eql(u8, "hello", "h\x65llo")}); // true
print("0x{x}\n", .{"\xff"[0]}); // non-UTF-8 strings are possible with \xNN notation.
print("{u}\n", .{'⚡'});
print("{}\n", .{mem.eql(u8, "hello", "h\x65llo")}); // true
print("{}\n", .{mem.eql(u8, "💯", "\xf0\x9f\x92\xaf")}); // also true
const invalid_utf8 = "\xff\xfe"; // non-UTF-8 strings are possible with \xNN notation.
print("0x{x}\n", .{invalid_utf8[1]}); // indexing them returns individual bytes...
print("0x{x}\n", .{"💯"[1]}); // ...as does indexing part-way through non-ASCII characters
}
{#code_end#}
{#see_also|Arrays|Source Encoding#}