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POboost interprocess unordered_map string
 

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  1. POboost interprocess unordered_map string
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    <p>I am trying to create a unordered_map in shared memory using Boost Interprocess library. Here, is the code, which I'm trying to use (taking examples from Boost Interprocess documentation):</p> <pre><code>#include &lt;boost/interprocess/managed_shared_memory.hpp&gt; #include &lt;boost/interprocess/allocators/allocator.hpp&gt; #include &lt;functional&gt; #include &lt;boost/functional/hash.hpp&gt; #include &lt;boost/unordered_map.hpp&gt; #include &lt;iostream&gt; #include &lt;string&gt; #include &lt;boost/interprocess/containers/string.hpp&gt; namespace bipc = boost::interprocess; typedef bipc::allocator&lt;char, bipc::managed_shared_memory::segment_manager&gt; CharAllocator; typedef bipc::basic_string&lt;char, std::char_traits&lt;char&gt;, CharAllocator&gt; ShmemString; struct Person { int age; ShmemString name; double salary; Person(int i, double sal, const char* s, const char_allocator&amp; a) : age(i), name(s, a), salary(sal) { } void print() {} } typedef ShmemString KeyType; typedef Person MappedType; typedef std::pair&lt; KeyType, MappedType &gt; MapPersonType; typedef bipc::allocator&lt; MapPersonType, bipc::managed_shared_memory::segment_manager &gt; ShMemAllocator; typedef boost::unordered_map&lt; KeyType, MappedType, boost::hash&lt;KeyType&gt;, std::equal_to&lt;KeyType&gt;, ShMemAllocator &gt; PersonMap; </code></pre> <p>This is what I'm trying to do in the main program:</p> <pre><code>int main() { bipc::managed_shared_memory segment(bipc::create_only, "MySharedMemory", 65536); PersonMap *persons = segment.construct&lt;PersonMap&gt;("MyHashMap") ( 3, boost::hash&lt;ShmemString&gt;(), std::equal_to&lt;ShmemString&gt;() , segment.get_allocator&lt;MapPersonType&gt;()); char_allocator alloc(segment.get_allocator&lt;char&gt;()); Person p1(20, 10000, "ABC", alloc); persons-&gt;insert(MapPersonType(ShmemString("Person1", alloc), p1)); } </code></pre> <p>Using the above code, I'm able to create an unordered_map in shared memory. However, when I am trying to access the map, I need to use a syntax like</p> <pre><code>persons-&gt;at(ShmemString("H", segment.get_allocator&lt;char&gt;())).print(); </code></pre> <p>However, I would prefer to do this with a std::string, which results in compilation errors:</p> <pre><code>persons-&gt;at(std::string("H")).print(); </code></pre> <p>Is it possible to write the above statement, i.e. accessing the map allocated in shared memory with std::string?</p>
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    1. COI posted this on boost-users mailing list. And, got an answer from Boost.Interprocess author that this cannot be done.
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