>, it is guaranteed that
<code>n == int.parse(n.toRadixString(r), radix: r)</code>.</p>
<p>If the <code>source</code> string does not contain a valid integer literal,
optionally prefixed by a sign, a <a href="dart-core/FormatException-class.html">FormatException</a> is thrown
(unless the deprecated <code>onError</code> parameter is used, see below).</p>
<p>Instead of throwing and immediately catching the <a href="dart-core/FormatException-class.html">FormatException</a>,
instead use <a href="dart-core/int/t