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  1. #include <iostream>
  2.     struct BigObj
  3.     {
  4.         BigObj() : m_useCount(0) {}
  5.  
  6.         int m_useCount;
  7.         int m_stuff[4096];
  8.     };
  9.  
  10.     void BigObjByValue(BigObj b)
  11.     {
  12.         b.m_useCount++;
  13.         std::cout << "BigObjByValue " << (&b) << ". m_useCount is now " << b.m_useCount << std::endl;
  14.     }
  15.  
  16.     void BigObjByPtr(BigObj* b)
  17.     {
  18.         b->m_useCount++;
  19.         std::cout << "BigObjByValue " << (b) << ". m_useCount is now " << b->m_useCount << std::endl;
  20.     }
  21.  
  22.     void BigObjByConstPtr(const BigObj* b)
  23.     {
  24.         //b->m_useCount++; // compiler won't allow this, try uncommenting.
  25.         std::cout << "BigObjByValue " << (b) << ". m_useCount is now " << b->m_useCount << std::endl;
  26.     }
  27.  
  28.     int main()
  29.     {
  30.         BigObj mainB;
  31.         std::cout << "Created mainB at " << (&mainB) << " useCount = " << mainB.m_useCount << std::endl;
  32.  
  33.         BigObjByValue(mainB);
  34.         std::cout << "in main, m_useCount = " << mainB.m_useCount << std::endl;
  35.  
  36.         BigObjByPtr(&mainB);
  37.         std::cout << "in main, m_useCount = " << mainB.m_useCount << std::endl;
  38.  
  39.         BigObjByConstPtr(&mainB);
  40.         std::cout << "in main, m_useCount = " << mainB.m_useCount << std::endl;
  41.  
  42.         return 0;
  43.     }
  44.  
Success #stdin #stdout 0s 3296KB
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stdin
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Standard input is empty
stdout
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Created mainB at 0xbfe1eb0c useCount = 0
BigObjByValue 0xbfe1aaf0. m_useCount is now 1
in main, m_useCount = 0
BigObjByValue 0xbfe1eb0c. m_useCount is now 1
in main, m_useCount = 1
BigObjByValue 0xbfe1eb0c. m_useCount is now 1
in main, m_useCount = 1
https://ideone.com/SjkoNq
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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