Comparison of programming languages (associative array): Difference between revisions

Revision as of 21:50, 4 August 2020

Revision as of 19:14, 6 August 2020

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===Rust===

The [[Rust (programming language)|Rust]] standard library provides a hash map (<code>std::collections::HashMap</code> and a [[B-tree]] map (<code>std::collections::BTreeMap</code>). They share several methods with the same names, but have different requirements for the types of keys that can be inserted. The <code>HashMap</code> requires keys to implement the <code>Eq</code> ([[equivalence relation]]) and <code>Hash</code> (hashability) traits and it stores entries in an unspecified order, and the <code>BTreeMap</code> requires the <code>Ord</code> trait for its keys and it stores entries in an order defined by the key type. The order is reflected by the default iterators.

[[Rust (programming language)|Rust]] has a hash map:

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</syntaxhighlight>

The default iterators visit all entries as tuples. The <code>HashMap</code> iterators visit entries in an unspecified order: and the <code>BTreeMap</code> iterator visits entries in the order defined by the key type.

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for (name, number) in &phone_book {

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There is also an iterator for keys:

Iterating through all the keys of the hash map:

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for name in phone_book.keys() {