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  1. /*
  2. VC2010, release, optimization /ox
  3. output of disable counter
  4. img1 50
  5. img2 57
  6. img3 45
  7. img4 16
  8. img1[y][x]= 7
  9. img3[y][x]= 6
  10. img4[y*n+x]= 10
  11. img1 75
  12. img2 63
  13. img3 49
  14. img4 16
  15. img1[y][x]= 8
  16. img3[y][x]= 7
  17. img4[y*n+x]= 10.
  18. */
  19. #include <iostream>
  20. #include <time.h>
  21. #include <vector>
  22. using namespace std;
  23. static long long ctr=0;
  24. static long long cpy=0;
  25. static long long assign=0;
  26. struct Pixel { 
  27.     int x,y,z;
  28.     Pixel():x(0),y(0),z(0){ 
  29.         //ctr++;
  30.     }
  31.     //Pixel(const Pixel& p) {
  32.     //    x=p.x,y=p.y,z=p.z;
  33.     //    cpy++;
  34.     //}
  35.     //Pixel& operator=(const Pixel& p) {
  36.     //    x=p.x,y=p.y,z=p.z;
  37.     //    assign++;
  38.     //    return *this;
  39.     //}
  40. };
  41. int main()
  42. {
  43.     int n = 2048;
  44.     Pixel c; 
  45.     clock_t t;
  46.     for (int i = 0; i < 2; ++i)
  47.     {
  48.         // (1) vector<vector>(n,vector<>(n))
  49.         ctr = cpy = assign = 0;
  50.         t = clock();
  51. 	    vector<vector<Pixel>> img1(n, vector<Pixel>(n));
  52.         cout << "img1 " << clock()-t << "\n"; 
  53.         //cout << "ctr=" << ctr << " cpy=" << cpy << " assign=" << assign << " loop=" << 0 << "\n\n";
  54.  
  55.         // (2) reserve then push_back
  56.         ctr = cpy = assign = 0;
  57.         t = clock();
  58.         vector<vector<Pixel>> img2(n);
  59. 	    for (int y = 0; y < n; ++y)
  60. 		    img2[y].reserve(n);
  61. 	    for (int y=0; y<n; ++y)
  62.             for (int x=0; x<n; ++x)
  63.                 img2[y].push_back(c);
  64.         cout << "img2 " << clock()-t << "\n";
  65.         //cout << "ctr=" << ctr << " cpy=" << cpy << " assign=" << assign << " loop=" << 0 << "\n\n";
  66.  
  67.         // (3) build 2D array by pointer array
  68.         ctr = cpy = assign = 0;
  69.         t = clock();
  70.         Pixel** img3 = new Pixel*[n];
  71.         for (int y = 0; y < n; ++y) img3[y] = new Pixel[n];
  72.         cout << "img3 " << clock()-t << "\n";
  73.         //cout << "ctr=" << ctr << " cpy=" << cpy << " assign=" << assign << " loop=" << 0 << "\n\n";
  74.  
  75.         // (4) 1D array
  76.         ctr = cpy = assign = 0;
  77.         t = clock();
  78.         Pixel* img4 = new Pixel[n*n];
  79.         cout << "img4 " << clock()-t << "\n";
  80.         //cout << "ctr=" << ctr << " cpy=" << cpy << " assign=" << assign << " loop=" << 0 << "\n\n";
  81.  
  82.         // vector<vector<>> [y][x]
  83.         ctr = cpy = assign = 0;
  84.         t = clock();
  85. 	    for (int y=0; y<n; ++y)
  86.             for (int x=0; x<n; ++x)
  87.                 img1[y][x] = c;
  88.         cout << "img1[y][x]= " << clock()-t << "\n";
  89.         //cout << "ctr=" << ctr << " cpy=" << cpy << " assign=" << assign << " loop=" << 0 << "\n\n";
  90.  
  91.         // Pixel** by [y][x]
  92.         ctr = cpy = assign = 0;
  93.         t = clock();
  94. 	    for (int y=0; y<n; ++y)
  95.             for (int x=0; x<n; ++x)
  96.                 img3[y][x] = c;
  97.         cout << "img3[y][x]= " << clock()-t << "\n";
  98.         //cout << "ctr=" << ctr << " cpy=" << cpy << " assign=" << assign << " loop=" << 0 << "\n\n";
  99.  
  100.         // Pixel * by [y*w+x]
  101.         ctr = cpy = assign = 0;
  102.         t = clock();
  103. 	    for (int y=0; y<n; ++y)
  104.             for (int x=0; x<n; ++x)
  105.                 img4[y*n+x] = c;
  106.         cout << "img4[y*n+x]= " << clock()-t << "\n";
  107.         //cout << "ctr=" << ctr << " cpy=" << cpy << " assign=" << assign << " loop=" << 0 << "\n\n";
  108.  
  109.  
  110.         for (int y = 0; y < n; ++y) delete [] img3[y];
  111.         delete [] img3;
  112.         delete [] img4;
  113.  
  114.     }
  115.     system("pause");
  116.     return 1;
  117. }
Runtime error #stdin #stdout #stderr 0.49s 3476KB
comments (?)
stdin
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Standard input is empty
stdout
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img1 40000
img2 50000
img3 50000
img4 30000
img1[y][x]= 20000
img3[y][x]= 20000
img4[y*n+x]= 20000
img1 50000
img2 50000
img3 40000
img4 40000
img1[y][x]= 20000
img3[y][x]= 20000
img4[y*n+x]= 20000
stderr
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sh: pause: not found
https://ideone.com/qSW5fo
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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