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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <time.h>
  4.  
  5. #define N 10000000
  6. #define M 6
  7.  
  8. int cnt[N];
  9. int sum = 0;
  10.  
  11. void func1()
  12. {
  13.   sum++;
  14. }
  15.  
  16. void func2()
  17. {
  18.   sum--;
  19. }
  20.  
  21. clock_t now(void)
  22. {
  23.   return clock();
  24. }
  25.  
  26. double ms(clock_t t1, clock_t t2)
  27. {
  28.   return (t2 - t1) / CLOCKS_PER_SEC;
  29. }
  30.  
  31. int main(void)
  32. {
  33.   void (*func[])(void) = { func1, func2 };
  34.   int i, j;
  35.   clock_t beg;
  36.  
  37.   for (i = 0; i < N; i++)
  38.     cnt[i] = i % 2; // call altenatively
  39.  
  40.   puts("Call 0101010101....");
  41.   beg = now();
  42.   for (j = 0; j < M; j++)
  43.     for (i = 0; i < N; i++)
  44.       func[cnt[i]]();
  45.   printf("%.3fms\n", ms(beg, now()));
  46.  
  47.   printf("sum = %d\n", sum);
  48.   sum = 0;
  49.  
  50.   for (i = 0; i < N; i++)
  51.     cnt[i] = (i % 3) ? 1 : 0; // call one in three times
  52.  
  53.   puts("Call 001001001....");
  54.   beg = now();
  55.   for (j = 0; j < M; j++)
  56.     for (i = 0; i < N; i++)
  57.       func[cnt[i]]();
  58.   printf("%.3fms\n", ms(beg, now()));
  59.  
  60.   printf("sum = %d\n", sum);
  61.   sum = 0;
  62.  
  63.   for (i = 0; i < N; i++)
  64.     cnt[i] = ((i % 4) == 0 || (i % 4) == 1) ? 1 : 0;
  65.  
  66.   puts("Call 00110011....");
  67.   beg = now();
  68.   for (j = 0; j < M; j++)
  69.     for (i = 0; i < N; i++)
  70.       func[cnt[i]]();
  71.   printf("%.3fms\n", ms(beg, now()));
  72.  
  73.   printf("sum = %d\n", sum);
  74.   sum = 0;
  75.  
  76.   srand(time(NULL));
  77.   for (i = 0; i < N; i++)
  78.     cnt[i] = (rand() >> 3) % 2; // call in random
  79.  
  80.   puts("Call in Random");
  81.   beg = now();
  82.   for (j = 0; j < M; j++)
  83.     for (i = 0; i < N; i++)
  84.       func[cnt[i]]();
  85.   printf("%.3fms\n", ms(beg, now()));
  86.  
  87.   printf("sum = %d\n", sum);
  88.  
  89.   return 0;
  90. }
  91.  
Success #stdin #stdout 2.15s 41352KB
comments (?)
stdin
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Standard input is empty
stdout
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Call 0101010101....
0.000ms
sum = 0
Call 001001001....
0.000ms
sum = -19999992
Call 00110011....
0.000ms
sum = 0
Call in Random
0.000ms
sum = -3096
https://ideone.com/D4wF8o
language:
C (gcc 8.3)
created:
10 years ago
visibility:
public

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