map Size in Rust 1.55

In Rust 1.55, you can get the size of a hash (also known as a HashMap) using the len method. Here's an example:

use std::collections::HashMap;
fn main() {

    let mut hash_map = HashMap::new();

    hash_map.insert("key1", "value1");

    hash_map.insert("key2", "value2");

    hash_map.insert("key3", "value3");
let hash_size = hash_map.len();

    println!("The hash map size is {}", hash_size);

}

In this example, we create a new HashMap called hash_map and insert three key-value pairs into it. We then call the len method on hash_map and store the result in a variable called hash_size. Finally, we use println! to print the size of the hash map. The output will be:

The hash map size is 3

Note that the len method returns the number of key-value pairs in the hash map. If you want to get the actual size of the hash table (i.e. the number of buckets), you can use the capacity method instead.