title: How to check if C string is empty
body: <p>I'm writing a very small program in C that needs to check if a certain string is empty. For the sake of this question, I've simplified my code:</p>
  
  <pre><code>#include &lt;stdio.h&gt;
  #include &lt;string&gt;
  
  int main() {
    char url[63] = {'\0'};
    do {
      printf("Enter a URL: ");
      scanf("%s", url);
      printf("%s", url);
    } while (/*what should I put in here?*/);
  
    return(0);
  }
  </code></pre>
  
  <p>I want the program to stop looping if the user just presses enter without entering anything. </p>