rustHow to use a tuple as a key in a Rust HashMap?
Tuples can be used as keys in a Rust HashMap by implementing the Hash
and Eq
traits. This can be done by using the #[derive(Hash, Eq)]
annotation on the tuple struct.
#[derive(Hash, Eq)]
struct TupleStruct(i32, i32);
use std::collections::HashMap;
let mut map = HashMap::new();
let key = TupleStruct(1, 2);
map.insert(key, "value");
The example code above creates a tuple struct TupleStruct
with two i32
fields, and implements the Hash
and Eq
traits on it. Then, a HashMap
is created and a key is created from the TupleStruct
. Finally, the key is used to insert a value into the HashMap
.
#[derive(Hash, Eq)]
: Annotation to implement theHash
andEq
traits on a tuple struct.TupleStruct(i32, i32)
: Tuple struct with twoi32
fields.HashMap::new()
: Creates a newHashMap
.let key = TupleStruct(1, 2)
: Creates a key from theTupleStruct
.map.insert(key, "value")
: Inserts a value into theHashMap
using the key.
Helpful links
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