Rust errors / Patterns and matching
Rust compiler error · checked with rustc 1.99.0
Rust error E0527: pattern requires 2 elements but array has 4
What it meansThe number of elements in an array or slice pattern differed from the number of elements in the array being matched.
What rustc prints
error[E0527]: pattern requires 2 elements but array has 4
--> main.rs:5:6
|
5 | &[a, b] => { // error: pattern requires 2 elements but array
| ^^^^^^ expected 4 elementsReal output of rustc 1.99.0 compiling the official example below (2021 edition). Your names and line numbers will differ; the first line is the part to match.
The compiler team's explanation
The number of elements in an array or slice pattern differed from the number of elements in the array being matched.
Example of erroneous code:
let r = &[1, 2, 3, 4];
match r {
&[a, b] => { // error: pattern requires 2 elements but array
// has 4
println!("a={}, b={}", a, b);
}
}Ensure that the pattern is consistent with the size of the matched array. Additional elements can be matched with ..:
let r = &[1, 2, 3, 4];
match r {
&[a, b, ..] => { // ok!
println!("a={}, b={}", a, b);
}
}From rustc --explain E0527 (1.99.0), part of the Rust project, MIT or Apache-2.0. Official page.
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