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History of Idiom 8 > diff from v43 to v44

Edit summary for version 44 by programming-idioms.org:
[Rust] Fix demo
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Version 43

2018-12-17, 18:14:33

Version 44

2018-12-30, 11:40:42

Idiom #8 Initialize a new map (associative array)

Declare a new map object x, and provide some (key, value) pairs as initial content.

Idiom #8 Initialize a new map (associative array)

Declare a new map object x, and provide some (key, value) pairs as initial content.

Extra Keywords
table dictionary hash
Extra Keywords
table dictionary hash
Imports 
use std::collections::BTreeMap;
Imports 
use std::collections::BTreeMap;
Code 
let mut x = BTreeMap::new();
x.insert("one", 1);
x.insert("two", 2);
Code 
let mut x = BTreeMap::new();
x.insert("one", 1);
x.insert("two", 2);
Comments bubble
Something different than a BTreeMap might be used, depending on the usage.

The function new of the type BTreeMap returns a usable map.
The map is stored mutable in the variable x.

Maps in Rust are generic but the type is determined by the compiler based on the later usage.
A line such as `x.insert(1, "one")` would therefore not compile.
Comments bubble
Something different than a BTreeMap might be used, depending on the usage.

The function new of the type BTreeMap returns a usable map.
The map is stored mutable in the variable x.

Maps in Rust are generic but the type is determined by the compiler based on the later usage.
A line such as `x.insert(1, "one")` would therefore not compile.
Demo URL
https://play.rust-lang.org/?code=use%20std%3A%3Acollections%3A%3ABTreeMap%3B%0A%0Afn%20main()%20%7B%0A%20%20%20%20let%20mut%20x%20%3D%20BTreeMap%3A%3Anew()%3B%0A%20%20%20%20x.insert(%22one%22%2C%201)%3B%0A%20%20%20%20x.insert(%22two%22%2C%202)%3B%0A%
Demo URL
https://play.rust-lang.org/?version=stable&mode=debug&edition=2015&gist=9186f79202d93bc33b1558428c40da93