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  1. #include <iostream>
  2. #include <string>
  3. #include <utility>
  4. #include <time.h>
  5.  
  6. std::string func1(const std::string& arg) {
  7.     std::string test(arg);
  8.     return test;
  9. }
  10.  
  11. template <typename T>
  12. std::string func2(T&& arg) {
  13.     std::string test(std::forward<T&>(arg));
  14.     return test;
  15. }
  16.  
  17. void wrap1(const std::string& arg) {
  18.     func1(arg);
  19. }
  20.  
  21. template <typename T>
  22. void wrap2(T&& arg) {
  23.     func2(std::forward<T&>(arg));
  24. }
  25.  
  26. int main()
  27. {
  28.      auto n = 100000000;
  29.  
  30.      /// Passing rvalue
  31.      std::cout << "Passing rvalue!" << std::endl;
  32.  
  33.      // Test const l value
  34.      auto t = clock();
  35.      for (int i = 0; i < n; ++i)
  36.          wrap1("test");
  37.      std::cout << "const l value: " << clock() - t << std::endl;
  38.  
  39.      // Test rvalue forwarding
  40.      t = clock();
  41.      for (int i = 0; i < n; ++i)
  42.          wrap2("test");
  43.      std::cout << "rvalue forwarding: " <<  clock() - t << std::endl;
  44.  
  45.      std::cout << "Passing lvalue!" << std::endl;
  46.  
  47.      /// Passing lvalue
  48.      std::string arg = "test";
  49.  
  50.      // Test const l value
  51.      t = clock();
  52.      for (int i = 0; i < n; ++i)
  53.          wrap1(arg);
  54.      std::cout << "const l value: " << clock() - t << std::endl;
  55.  
  56.      // Test rvalue forwarding
  57.      t = clock();
  58.      for (int i = 0; i < n; ++i)
  59.          wrap2(arg);
  60.      std::cout << "rvalue forwarding: " << clock() - t << std::endl;
  61.  
  62. }
Success #stdin #stdout 3.48s 15240KB
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stdin
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Standard input is empty
stdout
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Passing rvalue!
const l value: 1357465
rvalue forwarding: 669589
Passing lvalue!
const l value: 744105
rvalue forwarding: 713189
https://ideone.com/X1yzPe
language:
C++ (gcc 8.3)
created:
7 years ago
visibility:
public

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