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  1. #include <iostream>
  2. #include <string>
  3. #include <cstring>
  4.  
  5. const int size = 100000000;
  6.  
  7. static char s_str[size];
  8.  
  9. std::string test1()
  10. {
  11.     return std::string(s_str);
  12. }
  13.  
  14. void test2(std::string& s)
  15. {
  16.     s = s_str;
  17. }
  18.  
  19. int main()
  20. {
  21.     memset(s_str, 'x', size - 1);
  22.  
  23.     std::string s(s_str);
  24.     clock_t c1, c2, c3, c4, c5, c6;
  25.  
  26.     // コピー
  27.     c1 = clock();
  28.     for (int i = 0; i < 10; i++) {
  29.         s = static_cast<const std::string&>(test1());
  30.     }
  31.     c2 = clock();
  32.  
  33.     // ムーブ
  34.     c3 = clock();
  35.     for (int i = 0; i < 10; i++) {
  36.         s = test1();
  37.     }
  38.     c4 = clock();
  39.  
  40.     // バッファの再利用
  41.     c5 = clock();
  42.     for (int i = 0; i < 10; i++) {
  43.         test2(s);
  44.     }
  45.     c6 = clock();
  46.  
  47.     printf("コピー : %d\n", static_cast<int>(c2 - c1));
  48.     printf("ムーブ : %d\n", static_cast<int>(c4 - c3));
  49.     printf("再利用 : %d\n", static_cast<int>(c6 - c5));
  50. }
  51.  
Success #stdin #stdout 3.76s 100480KB
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Standard input is empty
stdout
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コピー : 1310000
ムーブ : 1320000
再利用 : 890000
https://ideone.com/Wx8T03
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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