rustHow to create a nested HashMap in Rust?

Nested HashMap in Rust can be created using the HashMap::new() method. The following example code creates a nested HashMap with two levels of nesting:

use std::collections::HashMap;

let mut map = HashMap::new();

let mut inner_map = HashMap::new();
inner_map.insert("key1", "value1");
inner_map.insert("key2", "value2");

map.insert("inner_map", inner_map);

println!("{:?}", map);

Output example

{"inner_map": {"key1": "value1", "key2": "value2"}}

Code explanation

1. use std::collections::HashMap; - imports the HashMap type from the std::collections module.
2. let mut map = HashMap::new(); - creates a new empty HashMap and stores it in the map variable.
3. let mut inner_map = HashMap::new(); - creates a new empty HashMap and stores it in the inner_map variable.
4. inner_map.insert("key1", "value1"); - inserts a key-value pair into the inner_map HashMap.
5. map.insert("inner_map", inner_map); - inserts the inner_map HashMap into the map HashMap.
6. println!("{:?}", map); - prints the contents of the map HashMap.

Helpful links

• Rust HashMap Documentation

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