title: Why do I need underscores in swift?
body: <p><a href="https://www.weheartswift.com/tuples-enums/" rel="noreferrer">Here</a> it says, "Note: the <code>_</code> means “I don’t care about that value”", but coming from JavaScript, I don't understand what that means.</p>
  
  <p>The only way I can get these functions to print was by using the underscores before the parameters:</p>
  
  <pre><code>func divmod(_ a: Int, _ b:Int) -&gt; (Int, Int) {
      return (a / b, a % b)
  }
  
  print(divmod(7, 3))
  print(divmod(5, 2))
  print(divmod(12,4))
  </code></pre>
  
  <p>Without the underscores I have to write it like this to avoid any errors:</p>
  
  <pre><code>func divmod(a: Int, b:Int) -&gt; (Int, Int) {
      return (a / b, a % b)
  }
  
  print(divmod(a: 7, b: 3))
  print(divmod(a: 5, b: 2))
  print(divmod(a: 12,b: 4))
  </code></pre>
  
  <p>I don't understand this underscore usage. When, how and why do I use these underscores? </p>