How to compare 2 different String literals byte by byte in RUST

I entered two string literals and converted them into arrays of bytes and now I'm trying to compare both arrays bytes to check for a match. If they match successfully, I want to save it into an unknown size array find, but it is not saving:

fn main() {
    let mut m: u8 = 0;
    // enter the first_name
    let alpha = "fawad";
    //covert name1 into array bytes
    let name1 = alpha.as_bytes();
    // enter the second_name
    let input = String::new();
    //covert name2 into array bytes
    let name2 = input.as_bytes();
    //want to create an unknown size of an array
    let find: Box<[u8]>;
    for (i, &place1) in name1.iter().enumerate() {
        let place1 = name1[i];
        for (j, &place2) in name2.iter().enumerate() {
            let place2 = name2[j];
            if place1 == place2 {
                let find = place2;
                m = m + 1;
            } else {
                break;
            }
        }
    }
    println!("comparison shows {:?}", find);
}

I get:

error: expected one of `:`, `;`, `=`, or `@`, found `[`
  --> src\main.rs:17:13

   |
17 |     let find[] : Box<[u8]>;
   |             ^ expected one of `:`, `;`, `=`, or `@` here

Solution

The compiler message is not reproducable, yet your code reveals some misunderstandings. Here some hints how you could change it:

You want an array of unknown size (and it shall probably contain the bytes already matched, so it must be mutable):

replace let find : Box<[u8]>; by let mut find = Vec::new();

You want to iterate the bytes of name1 and name2

replace for (i, &place1) in name1.iter().enumerate() by for &place1 in name1.iter()
replace for (i, &place2) in name2.iter().enumerate() by for &place2 in name2.iter()

let variable = ... shadows all former definitions of variable. You do not want to shadow the variables place1, place2 you want to use these variables.

remove let place1 = name1[i];
remove let place2 = name2[j];

You want to add the matching byte to the array find. Your code will again shadow the definition of find. So

replace let find = place2; by find.push(place2);