title: How to test the length of a new line when using u_fgets in ICU4C ustdio.h?
body: <p>In ICU4C,</p>
  
  <pre><code>UChar * u_fgets(UChar *s, int32_t n, UFILE *f)
  </code></pre>
  
  <p>will read one line from <code>f</code> into buffer <code>s</code>, which size is <code>n</code>.</p>
  
  <p>But how can I know this one line's length ?</p>
  
  <p>What will happen if <code>n</code> is not enough for this one line ?</p>