I'm writing a string into QSharedMemory and after writing, I need to read it from boost program. I tried this, but didn't work.
I read the data in shared memory from the same Qt program, and I see the string.

Below is Qt program, from which I'm writing into shared memory with key ShrdMem
Qt Code: 
  1. // Slot, which is invoked on click of button.
  2. void CDialog::loadString()
  3. {
  4.     if(sharedMemory.isAttached())
  5.     {
  6.         if(!sharedMemory.detach())
  7.         {
  8.             lbl->setText("Unable to detach from Shared Memory");
  9.             return;
  10.         }
  11.     }
  12.  
  13.     char sString[] = "my string";
  14.  
  15.     QBuffer buffer;
  16.     buffer.open(QBuffer::ReadWrite);
  17.  
  18.     QDataStream out(&buffer);
  19.     out << sString;
  20.  
  21.     int size = buffer.size();
  22.     qDebug() << size;
  23.  
  24.     if(!sharedMemory.create(size))
  25.     {
  26.         lbl->setText("Unable to create shared memory segment");
  27.         qDebug() << lbl->text();
  28.     }
  29.     sharedMemory.lock();
  30.     char *to = (char *) sharedMemory.data();
  31.     const char *from = buffer.data();
  32.     memcpy(to, from, qMin(sharedMemory.size(), size));
  33.     sharedMemory.unlock();
  34.  
  35.     char * str;
  36.     QDataStream in(&buffer);
  37.     sharedMemory.lock();
  38.     buffer.setData((char *)sharedMemory.constData(), sharedMemory.size());
  39.     buffer.open(QBuffer::ReadOnly);
  40.     in >> str;
  41.     sharedMemory.unlock();
  42.     qDebug() << str;
  43. }
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I'm trying to read the ShrdMem using Boost as shown below.
Qt Code: 
  1. //NQShrdMem.cpp
  2. int main()
  3. {
  4.   boost::interprocess::shared_memory_object shdmem(boost::interprocess::open_only, "ShrdMem", boost::interprocess::read_only);
  5.  
  6.   boost::interprocess::offset_t size; 
  7.   if (shdmem.get_size(size)) 
  8.     std::cout << "Shared Mem Size: " << size << std::endl; 
  9.  
  10.   boost::interprocess::mapped_region region2(shdmem, boost::interprocess::read_only); 
  11.   char *i2 = static_cast<char *>(region2.get_address()); 
  12.   std::cout << i2 << std::endl;
  13.   return 0;
  14. }
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I'm compiling the Boost program in cygwin, using g++:
Qt Code: 
  1. g++ -I /cygdrive/c/boost/boost_1_53_0/ NQShrdMem.cpp -o NQShrdMem /cygdrive/c/boost_lib/boost/bin.v2/libs/date_time/build/gcc-mingw-4.7.2/release/link-static/threading-multi/libboost_date_time-mgw47-mt-1_53.a
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Kindly help me. Thank you.