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  1. #include <iostream>
  2. #include <vector>
  3.  
  4. struct A{
  5.         A(int id):  id(id){
  6.                 std::cout << id << ": constructing" << std::endl;
  7.         }
  8.  
  9.         ~A(){
  10.                 auto &s = std::cout << id << ": destroying";
  11.                 if (isCopy)
  12.                         s << " a copy";
  13.                 s << std::endl;
  14.         }
  15.  
  16.         A(const A& a) : id(a.id), isCopy(true) {
  17.                 std::cout << id << ": copy constructor" << std::endl;
  18.         }
  19. private:
  20.         int id;
  21.         bool isCopy = false;
  22. };
  23.  
  24. void Copy(){
  25.         std::cout << "Via copy" << std::endl;
  26.         std::vector<A> v;
  27.         v.reserve(3);
  28.         v.push_back(A(1));
  29.         v.push_back(A(2));
  30.         v.push_back(A(3));
  31. }
  32.  
  33. void Move(){
  34.         std::cout << std::endl;
  35.         std::cout << "Via move" << std::endl;
  36.         std::vector<A> v;
  37.         v.reserve(3);
  38.         v.emplace_back(4);
  39.         v.emplace_back(5);
  40.         v.emplace_back(6);
  41. }
  42.  
  43. int main(){
  44.         Copy();
  45.         Move();
  46.         return 0;
  47. }
  48.  
Success #stdin #stdout 0s 3436KB
comments (?)
stdin 
Standard input is empty
stdout 
Via copy
1: constructing
1: copy constructor
1: destroying
2: constructing
2: copy constructor
2: destroying
3: constructing
3: copy constructor
3: destroying
1: destroying a copy
2: destroying a copy
3: destroying a copy

Via move
4: constructing
5: constructing
6: constructing
4: destroying
5: destroying
6: destroying
https://ideone.com/ARzhL2
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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