How to convert a 4 element &[u8] into i32?

Question

I have an i32 that i pass to my keyvalue database.

let a = 1234i32;
db.put(&a.to_be_bytes());

But i get it back as &[u8], how to convert it back to i32?

---

update: this example pretty much does what i want.

use std::convert::TryInto;

fn read_be_i32(input: &[u8]) -> i32 {
    i32::from_be_bytes(input.try_into().unwrap())
}

Answer 1

Use i32::from_be_bytes and from this answer, TryFrom:

use std::convert::TryFrom;
fn main() {
    let a = 1234i32.to_be_bytes();
    let a_ref: &[u8] = &a;
    let b = i32::from_be_bytes(<[u8; 4]>::try_from(a_ref).expect("Ups, I did it again..."));
    println!("{}", b);
}

Playground