Which C++ Standard Library wrapper functions do you use?
<p><a href="http://stackoverflow.com/questions/2551775/c-appending-a-vector-to-a-vector">This question</a>, asked this morning, made me wonder which features you think are missing from the C++ Standard Library, and how you have gone about filling the gaps with wrapper functions. For example, my own utility library has this function for vector append:</p>

<pre><code>template &lt;class T&gt;
std::vector&lt;T&gt; &amp; operator += ( std::vector&lt;T&gt; &amp; v1,
                               const std::vector &lt;T&gt; &amp; v2 ) {
    v1.insert( v1.end(), v2.begin(), v2.end() );
    return v1;
}
</code></pre>

<p>and this one for clearing (more or less) any type - particularly useful for things like std::stack:</p>

<pre><code>template &lt;class C&gt;
void Clear( C &amp; c ) {
    c = C();
}
</code></pre>

<p>I have  a few more, but I'm interested in which ones you use? Please limit answers to <em>wrapper</em> functions - i.e. no more than a couple of lines of code.</p>
