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  1. #include <vector>
  2. #include <iostream>
  3. #include <cstring>
  4.  
  5. int main()
  6. {
  7.  
  8.     size_t num = 9999999;
  9.  
  10.  
  11.     //-----------------Наполнение вектора произвольными значениями--------
  12.  
  13.     std::vector<size_t>my_vector_rand;
  14.     my_vector_rand.resize(num);
  15.  
  16.     for (size_t i = 0; i < num; i++)
  17.     {
  18.         my_vector_rand[i] = rand() % 100;
  19.     }
  20.  
  21.     //-----------------------------------------------------------------------------------
  22.  
  23.  
  24.     int clock1;
  25.     int clock2;
  26.  
  27.  
  28.  
  29.  
  30.  
  31.     //-----------------------------------------------------------------
  32.     size_t* my_sizet_pionter1 = (size_t*)malloc(num * sizeof(size_t));
  33.  
  34.     clock1 = clock();
  35.     for (size_t i = 0; i < num; i++)
  36.     {
  37.         memcpy(&my_sizet_pionter1[i], &my_vector_rand[i], sizeof(size_t));
  38.     }
  39.     clock2 = clock();
  40.     std::cout << "time_memcpy_without_all:" << clock2 - clock1 << std::endl;
  41.     std::cout << my_sizet_pionter1[num - 1] << std::endl;
  42.     //-----------------------------------------------------------------
  43.  
  44.  
  45.  
  46.  
  47.  
  48.  
  49.     //-----------------------------------------------------------------
  50.     size_t* my_sizet_pionter2 = (size_t*)malloc(num * sizeof(size_t));
  51.  
  52.     memset(my_sizet_pionter2, 0, num * sizeof(size_t));
  53.     std::cout << my_sizet_pionter2[num - 1] << std::endl;     //Нужен, чтобы компилятор не оптимизировал вышестоящий memset.
  54.  
  55.  
  56.     clock1 = clock();
  57.     for (size_t i = 0; i < num; i++)
  58.     {
  59.         memcpy(&my_sizet_pionter2[i], &my_vector_rand[i], sizeof(size_t));
  60.     }
  61.     clock2 = clock();
  62.     std::cout << "time_memcpy_memset_zero:" << clock2 - clock1 << std::endl;
  63.     std::cout << my_sizet_pionter2[num - 1] << std::endl;
  64.     //-----------------------------------------------------------------
  65.  
  66.  
  67.  
  68.  
  69.     //-----------------------------------------------------------------
  70.     size_t* my_sizet_pionter3 = (size_t*)malloc(num * sizeof(size_t));
  71.  
  72.     memset(my_sizet_pionter3, 1, num * sizeof(size_t));
  73.     std::cout << my_sizet_pionter3[num - 1] << std::endl;     //Нужен, чтобы компилятор не оптимизировал вышестоящий memset.
  74.  
  75.     clock1 = clock();
  76.     for (size_t i = 0; i < num; i++)
  77.     {
  78.         memcpy(&my_sizet_pionter3[i], &my_vector_rand[i], sizeof(size_t));
  79.     }
  80.     clock2 = clock();
  81.     std::cout << "time_memcpy_memset_one:" << clock2 - clock1 << std::endl;
  82.     std::cout << my_sizet_pionter3[num - 1] << std::endl;
  83.     //-----------------------------------------------------------------
  84.  
  85.  
  86.  
  87.  
  88.  
  89.  
  90.     //-----------------------------------------------------------------
  91.     size_t* my_sizet_pionter4 = (size_t*)malloc(num * sizeof(size_t));
  92.  
  93.  
  94.     for (size_t i = 0; i < num; i++)
  95.     {
  96.         my_sizet_pionter4[i] = 0;
  97.     }
  98.     std::cout << my_sizet_pionter4[num - 1] << std::endl;     //Нужен, чтобы компилятор не оптимизировал вышестоящий цикл.
  99.  
  100.  
  101.  
  102.     clock1 = clock();
  103.     for (size_t i = 0; i < num; i++)
  104.     {
  105.         memcpy(&my_sizet_pionter4[i], &my_vector_rand[i], sizeof(size_t));
  106.     }
  107.     clock2 = clock();
  108.     std::cout << "time_memcpy_cycle_zero:" << clock2 - clock1 << std::endl;
  109.     std::cout << my_sizet_pionter4[num - 1] << std::endl;
  110.     //-----------------------------------------------------------------
  111.  
  112.  
  113.  
  114.  
  115.  
  116.     //-----------------------------------------------------------------
  117.     size_t* my_sizet_pionter5 = (size_t*)malloc(num * sizeof(size_t));
  118.  
  119.  
  120.     for (size_t i = 0; i < num; i++)
  121.     {
  122.         my_sizet_pionter5[i] = 1;
  123.     }
  124.     std::cout << my_sizet_pionter5[num - 1] << std::endl;     //Нужен, чтобы компилятор не оптимизировал вышестоящий цикл.
  125.  
  126.  
  127.     clock1 = clock();
  128.     for (size_t i = 0; i < num; i++)
  129.     {
  130.         memcpy(&my_sizet_pionter5[i], &my_vector_rand[i], sizeof(size_t));
  131.     }
  132.     clock2 = clock();
  133.     std::cout << "time_memcpy_cycle_one:" << clock2 - clock1 << std::endl;
  134.     std::cout << my_sizet_pionter5[num - 1] << std::endl;
  135.     //-----------------------------------------------------------------
  136. }
  137.  
Success #stdin #stdout 0.23s 471860KB
comments (?)
stdin
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Standard input is empty
stdout
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time_memcpy_without_all:13545
7
0
time_memcpy_memset_zero:12367
7
72340172838076673
time_memcpy_memset_one:14014
7
0
time_memcpy_cycle_zero:14065
7
1
time_memcpy_cycle_one:13890
7
https://ideone.com/OQXSbJ
language:
C++14 (gcc 8.3)
created:
2 years ago
visibility:
public

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