Question

How to get and use a hash code for an array and a vector of integers in Rust

Answer 1

use std::hash::{Hash, Hasher};
use std::collections::hash_map::DefaultHasher;

pub struct ArrayHashHelper;

impl ArrayHashHelper {

    pub fn get_array_hash_code(values: Option<&[i32]>) -> i32 {
        // Handle null input.
        let values = match values {
            Some(v) => v,
            None => return 0,
        };

        // HashCode provides a high-quality hash implementation.
        let mut hasher = DefaultHasher::new();

        // Add each element in order.
        // Order matters: [1,2,3] != [3,2,1].
        values.hash(&mut hasher);

        // Convert u64 hash to i32 to match the C# return type
        hasher.finish() as i32
    }

    pub fn main() {
        let numbers = vec![1, 2, 3, 4, 5];

        let hash_code = ArrayHashHelper::get_array_hash_code(Some(&numbers));

        println!("{}", hash_code);

        let array1 = [1, 2, 3];
        let array2 = [1, 2, 3];

        let hash1 = ArrayHashHelper::get_array_hash_code(Some(&array1));
        let hash2 = ArrayHashHelper::get_array_hash_code(Some(&array2));

        if hash1 == hash2 {
            println!("Arrays may be equal.");
        }

        if hash1 == hash2 && array1 == array2 {
            println!("Arrays are equal.");
        }
    }
}

fn main() {
    ArrayHashHelper::main();
}


/*
run:

-1606495798
Arrays may be equal.
Arrays are equal.

*/

 

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