title: Is it possible to define a constant value from the terminal?
body: <p>In order to create an array in rust it needs to have a predefined size:</p>
  
  <pre><code>arr = [u32; 4];
  </code></pre>
  
  <p>If instead of 4 I use a variable, it gives an error, unless it is a constant defined for example as:</p>
  
  <pre><code>const SIZE: usize = 4;
  </code></pre>
  
  <p>The question: <strong>is there a way to define the size of the array according to input from the terminal (command line arguments) when running the program?</strong> 
  My assumption is that the const has to be defined in compile time, so not using a const. Maybe using a slice this is possible? </p>