t_wの輪郭

Stringとu32の結合

+演算子では不可能。formatを使おう。

fn main() {
    let s1 = String::from("Hello, ");
    let s2 = 1234;
    let s3 = s1 + &s2;      // error!!!
    println!("{}", s3);     
}

error[E0308]: mismatched types
 --> src\main.rs:4:19
  |
4 |     let s3 = s1 + &s2;      // error!!!
  |                   ^^^ expected `str`, found integer
  |
  = note: expected reference `&str`
             found reference `&{integer}`