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    <p>IMO, you need to change the way your objects are stored. Something like the following:</p> <pre><code>std::map&lt;std::string, std::vector&lt;Composite&gt; &gt; </code></pre> <p>The key to the map is the prefix, and the index in the vector is the nth <code>Composite</code> object. You would need to provide a custom lookup function which split the passed in name.. e.g.</p> <pre><code>std::string query = "pipo_10"; </code></pre> <p>In your lookup function, </p> <pre><code>Composite* lookup(std::string const&amp; key) { // split the key to get the prefix and the index // lookup in the map using the prefix // return the index } </code></pre> <p>EDIT 1: To save all the string operations, you could define your own <em>custom key</em>, which is simply a pair (e.g, <code>std::pair&lt;std::string, int&gt;</code> which is the prefix and the index), and your lookup would simply use the values from this <em>key</em>.</p> <p><strike> EDIT 2: Thinking about this a little more, better to have a map of map, e.g.</p> <pre><code>std::map&lt;std::string, std::map&lt;int, Composite&gt; &gt; </code></pre> <p>Now instead of the index being an index in the vector, it's a lookup in the second map. This handles deletions better, the key will be the composite key as I said before (the pair). </strike></p> <p>Crediting @Steves' suggestion..</p> <pre><code>std::map&lt;std::pair&lt;std::string, int&gt;, Composite&gt; </code></pre> <p>Use the <code>lower_bound()</code> trick to locate the last index for the given <code>Composite</code></p>
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    1. POWhat is the best strategy to store objects ensuring unique name and being able to efficiently retrieve them later, in c++?
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    1. CO+1, but I prefer the `pair` as key over the map of vectors. I doubt that you want the names of all the `k+1 ... n` children to change if you delete the `k`th child from a set of `n` siblings, but nor would you want to have to arrange a scheme so that the vector can have "deleted" elements in the middle.
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      1. USSteve Jessop
    2. CO@SteveJessop, I was thinking about that, how would you locate the next index for a given prefix though (without counting all matching prefixes - which could be tricky)? May be it's better to have a map of map where the index in the second map is the nth `Composite`, true about the deleted `Composite` objects.. let me update..
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    3. CO`descendents.lower_bound(make_pair(prefix, INT_MAX))` finds a suitable slot to add a new descendent whose desired name is `prefix`. It doesn't re-use any slots that have been vacated, unless they happen to be at the end. If removal happens a lot then you could upgrade the `int` to `long long` to avoid ever overflowing.
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