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POC++ map erase(begin, end) not working
 

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    <p>I'm trying to do my life easier by using the C++ API for map. Through the <code>map.erase(begin, end)</code> method I'm hoping to delete all the entries between <code>[begin, end)</code>. So my method is implemented and <code>TabletKey</code> are defined below.</p> <pre><code> 79 void 80 ObjectFinder::flush(uint64_t tableId) { 81 82 RAMCLOUD_TEST_LOG("flushing object map"); 83 std::map&lt;TabletKey, ProtoBuf::Tablets::Tablet&gt;::iterator lower; 84 std::map&lt;TabletKey, ProtoBuf::Tablets::Tablet&gt;::iterator upper; 85 std::map&lt;TabletKey, ProtoBuf::Tablets::Tablet&gt;::iterator it; 86 KeyHash keyHash = Key::getHash(tableId, "", 0); 87 TabletKey key(tableId, keyHash); 88 89 std::cout &lt;&lt; "before the loop" &lt;&lt; std::endl; 90 for (it = tableMap.begin(); it != tableMap.end(); it++) { 91 std::cout &lt;&lt; it-&gt;first.first &lt;&lt; std::endl; 92 } 93 lower = tableMap.lower_bound(key); 94 upper = tableMap.upper_bound(key); 95 108 tableMap.erase(lower, upper); 109 std::cout &lt;&lt; "After the erase" &lt;&lt; std::endl; 110 for (it = tableMap.begin(); it != tableMap.end(); it++) { 111 std::cout &lt;&lt; it-&gt;first.first &lt;&lt; std::endl; 112 } } </code></pre> <p>However, the <code>id</code> values are not being deleted:</p> <pre><code>id = 99 before the loop 1 99 After the erase 1 99 </code></pre> <p>I wrote my own <code>comparison</code> function, to overload the default method:</p> <pre><code> 35 typedef std::pair&lt;uint64_t, KeyHash&gt; TabletKey; 36 37 /* 38 * The object CmpTabletKey is used to override the default comparison 39 * definition from the C++ Map. 40 */ 41 struct CmpTabletKey { 42 bool operator()(const TabletKey&amp; key1, const TabletKey&amp; key2) const { 43 return ((key1.first &lt; key2.first) || 44 (key1.first == key2.first &amp;&amp; key1.second &lt; key2.second)); } } </code></pre> <p>Could someone give me a clue why is <code>erase</code> not working as expected? Do I have to give the definition of <code>CmpTabletKey</code> to the <code>iterator</code> as well? <strong><em>Update</em></strong> This is my old implementation: It works nicely, and do what I want: However, it's a O(n) method, and I want a faster implementation:</p> <pre><code>117 std::map&lt;TabletKey, ProtoBuf::Tablets::Tablet&gt;::iterator it; 118 for (it = tableMap.begin(); it != tableMap.end(); ) { 119 if (tableId == it-&gt;first.first) { 120 tableMap.erase((it++)-&gt;first); 121 } else { 122 ++it; 123 } 124 } </code></pre>
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    1. UScybertextron
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    1. COWhat is "tableMap"?
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    2. COit's a `C++` map between a `TabletKey` and an object
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    3. COWhy are you blaming `erase`? Did you even check that the iterators have the expected values?
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