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The book was located under 'src/doc/trpl' because originally, it was going to be hosted under that URL. Late in the game, before 1.0, we decided that /book was a better one, so we changed the output, but not the input. This causes confusion for no good reason. So we'll change the source directory to look like the output directory, like for every other thing in src/doc.
1,020 B
1,020 B
% Slice patterns
If you want to match against a slice or array, you can use & with the
slice_patterns feature:
#![feature(slice_patterns)]
fn main() {
let v = vec!["match_this", "1"];
match &v[..] {
["match_this", second] => println!("The second element is {}", second),
_ => {},
}
}
The advanced_slice_patterns gate lets you use .. to indicate any number of
elements inside a pattern matching a slice. This wildcard can only be used once
for a given array. If there's an identifier before the .., the result of the
slice will be bound to that name. For example:
#![feature(advanced_slice_patterns, slice_patterns)]
fn is_symmetric(list: &[u32]) -> bool {
match list {
[] | [_] => true,
[x, inside.., y] if x == y => is_symmetric(inside),
_ => false
}
}
fn main() {
let sym = &[0, 1, 4, 2, 4, 1, 0];
assert!(is_symmetric(sym));
let not_sym = &[0, 1, 7, 2, 4, 1, 0];
assert!(!is_symmetric(not_sym));
}