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  1. #include <vector>
  2. #include <stdlib.h>
  3. #include <memory.h>
  4. #include <iostream>
  5.  
  6. int main()
  7. {
  8.  
  9.  size_t num = 9999999; 
  10.  
  11.  
  12. //-----------------Наполнение вектора произвольными значениями--------
  13.  
  14.     std::vector<size_t>my_vector_rand;
  15.     my_vector_rand.resize(num);
  16.  
  17.     for (size_t i = 0; i < num; i++)
  18.     {
  19.         my_vector_rand[i] = rand() % 100;
  20.     }
  21.  
  22.     size_t * my_vector_int = my_vector_rand.data();
  23.  
  24. //-----------------------------------------------------------------------------------
  25.  
  26.  
  27.     int clock1;
  28.     int clock2;
  29.  
  30.     //-----------------------------------------------------------------
  31.     size_t* my_sizet_pionter1 = (size_t*)malloc(num * sizeof(size_t));
  32.  
  33.     clock1 = clock();
  34.     for (size_t i = 0; i < num; i++)
  35.     {
  36.         memcpy(&my_sizet_pionter1[i], &my_vector_int[i], sizeof(size_t));
  37.     }
  38.     clock2 = clock();
  39.     std::cout << "time_memcpy_without_all: " << clock2 - clock1 << std::endl;
  40.     std::cout << my_sizet_pionter1[num - 1] << std::endl;
  41.     //-----------------------------------------------------------------
  42.  
  43.  
  44.  
  45.  
  46.  
  47.  
  48.     //-----------------------------------------------------------------
  49.     size_t* my_sizet_pionter2 = (size_t*)malloc(num * sizeof(size_t));
  50.  
  51.     memset(my_sizet_pionter2, 0, num * sizeof(size_t));
  52.     std::cout << my_sizet_pionter2[num - 1] << std::endl;     //Нужен, чтобы компилятор не оптимизировал вышестоящий memset.
  53.  
  54.  
  55.     clock1 = clock();
  56.     for (size_t i = 0; i < num; i++)
  57.     {
  58.         memcpy(&my_sizet_pionter2[i], &my_vector_int[i], sizeof(size_t));
  59.     }
  60.     clock2 = clock();
  61.     std::cout << "time_memcpy_memset_zero: " << clock2 - clock1 << std::endl;
  62.     std::cout << my_sizet_pionter2[num - 1] << std::endl;
  63.     //-----------------------------------------------------------------
  64.  
  65.  
  66.  
  67.  
  68.     //-----------------------------------------------------------------
  69.     size_t* my_sizet_pionter3 = (size_t*)malloc(num * sizeof(size_t));
  70.  
  71.     memset(my_sizet_pionter3, 1, num * sizeof(size_t));
  72.     std::cout << my_sizet_pionter3[num - 1] << std::endl;     //Нужен, чтобы компилятор не оптимизировал вышестоящий memset.
  73.  
  74.     clock1 = clock();
  75.     for (size_t i = 0; i < num; i++)
  76.     {
  77.         memcpy(&my_sizet_pionter3[i], &my_vector_int[i], sizeof(size_t));
  78.     }
  79.     clock2 = clock();
  80.     std::cout << "time_memcpy_memset_one: " << clock2 - clock1 << std::endl;
  81.     std::cout << my_sizet_pionter3[num - 1] << std::endl;
  82.     //-----------------------------------------------------------------
  83.  
  84.  
  85.  
  86.  
  87.  
  88.  
  89.     //-----------------------------------------------------------------
  90.     size_t* my_sizet_pionter4 = (size_t*)malloc(num * sizeof(size_t));
  91.  
  92.  
  93.     for (size_t i = 0; i < num; i++)
  94.     {
  95.         my_sizet_pionter4[i] = 0;
  96.     }
  97.     std::cout << my_sizet_pionter4[num - 1] << std::endl;     //Нужен, чтобы компилятор не оптимизировал вышестоящий цикл.
  98.  
  99.  
  100.  
  101.     clock1 = clock();
  102.     for (size_t i = 0; i < num; i++)
  103.     {
  104.         memcpy(&my_sizet_pionter4[i], &my_vector_int[i], sizeof(size_t));
  105.     }
  106.     clock2 = clock();
  107.     std::cout << "time_memcpy_cycle_zero: " << clock2 - clock1 << std::endl;
  108.     std::cout << my_sizet_pionter4[num - 1] << std::endl;
  109.     //-----------------------------------------------------------------
  110.  
  111.  
  112.  
  113.  
  114.  
  115.     //-----------------------------------------------------------------
  116.     size_t* my_sizet_pionter5 = (size_t*)malloc(num * sizeof(size_t));
  117.  
  118.  
  119.     for (size_t i = 0; i < num; i++)
  120.     {
  121.         my_sizet_pionter5[i] = 0;
  122.     }
  123.     std::cout << my_sizet_pionter5[num - 1] << std::endl;     //Нужен, чтобы компилятор не оптимизировал вышестоящий цикл.
  124.  
  125.  
  126.     clock1 = clock();
  127.     for (size_t i = 0; i < num; i++)
  128.     {
  129.         memcpy(&my_sizet_pionter5[i], &my_vector_int[i], sizeof(size_t));
  130.     }
  131.     clock2 = clock();
  132.     std::cout << "time_memcpy_cycle_one: " << clock2 - clock1 << std::endl;
  133.     std::cout << my_sizet_pionter5[num - 1] << std::endl;
  134.     //-----------------------------------------------------------------
  135. }
Success #stdin #stdout 0.23s 471928KB
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stdin
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Standard input is empty
stdout
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time_memcpy_without_all: 12734
7
0
time_memcpy_memset_zero: 12463
7
72340172838076673
time_memcpy_memset_one: 14224
7
0
time_memcpy_cycle_zero: 15984
7
0
time_memcpy_cycle_one: 13937
7
https://ideone.com/cLkzTC
language:
C++14 (gcc 8.3)
created:
2 years ago
visibility:
public

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