title: Placeholder issue
body: <p>I wanted to use a placeholder for the int <code>age</code>, but %i or %s are not working.</p>
  <p>This is my code :</p>
  <pre><code>#include &lt;cs50.h&gt;
  #include &lt;stdio.h&gt;
  
  int main(void)
  {
      int age = get_int(&quot;What is your age ?\n&quot;);
      printf(&quot;You are %i years old.\n&quot;);
  }
  </code></pre>
  <p>This is the error :</p>
  <pre><code>test1.c:7:22: error: more '%' conversions than data arguments [-Werror,-Wformat]
      printf(&quot;You are %i years old.\n&quot;);
                      ~^
  1 error generated.
  &lt;builtin&gt;: recipe for target 'test1' failed
  make: *** [test1] Error 1
  </code></pre>