title: I can't give multiples inputs in Rust
body: <p>I was writing a code in rust like a training and when I run the below code, the rust compile give me this erro message:</p>
  <pre><code>thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: ParseIntError { kind: InvalidDigit }', src/main.rs:8:41
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
  </code></pre>
  <p>Codigo:</p>
  <pre><code>use std::io;
  
  fn main() {
      let mut num_cases:String=String::from(&quot;&quot;);
      io::stdin().read_line(&amp;mut num_cases).expect(&quot;Ouve...&quot;);
      let num_cases:i32=num_cases.parse().unwrap();
  
      for i in 0..num_cases {
          let mut arr_lenght:String=String::from(&quot;&quot;);
          io::stdin().read_line(&amp;mut arr_lenght).expect(&quot;Erro...&quot;);
          println!(&quot;{}&quot;,arr_lenght);
         
          println!(&quot;{}&quot;, i);
      }
  }
  </code></pre>
  <p>I want know why this is happening? When I use just input out of loop none error appear, but when a try use the <code>read_line()</code> in for-loop, I take this error message.</p>