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  1.     #include <iostream>
  2.     #include <memory.h>
  3.  
  4.     struct B {
  5.         B() { std::cout << "B()" << std::endl; }
  6.         ~B() { std::cout << "~B()" << std::endl; }
  7.     };
  8.  
  9.     int main()
  10.     {
  11.         std::cout << "start main" << std::endl;
  12.         { // scope
  13.             std::cout << "start scope" << std::endl;
  14.             B b;
  15.             std::cout << "end scope" << std::endl;
  16.         } // end scope, b gets auto-destroyed.
  17.         std::cout << "end of first example." << std::endl << std::endl ;
  18.  
  19.         { // scope
  20.             std::cout << "start scope" << std::endl;
  21.             void* stackStorage = alloca(sizeof(B));
  22.             std::cout << "alloca'd" << std::endl;
  23.             B* b = new (stackStorage) B();
  24.             std::cout << "ctord" << std::endl;
  25.             b->~B(); // <-- we're responsible for dtoring this object.
  26.             std::cout << "end scope" << std::endl;
  27.         } // <-- b gets destroyed here, but it's just a pointer.
  28.         std::cout << "end main" << std::endl;
  29.     }
  30.  
Success #stdin #stdout 0s 3340KB
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stdin
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Standard input is empty
stdout
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start main
start scope
B()
end scope
~B()
end of first example.

start scope
alloca'd
B()
ctord
~B()
end scope
end main
https://ideone.com/ziNjkd
language:
C++14 (gcc 8.3)
created:
12 years ago
visibility:
public

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