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Exceptions Vs Returns

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  1. #include <iostream>
  2. #include <stdexcept>
  3.  
  4. struct SpaceWaster {
  5.     SpaceWaster(int l, bool b, SpaceWaster *p) : level(l), bad(b), prev(p) {}
  6.     // we want the destructor to do something
  7.     ~SpaceWaster() { prev = 0; }
  8.     int checkLevel() { return level == 0;}
  9.     int isBad() {return bad;}
  10.     int level;
  11.     bool bad;
  12.     SpaceWaster *prev;
  13. };
  14.  
  15. void thrower(SpaceWaster *current) {
  16.     if (current->checkLevel())
  17.     {
  18.         if (current->isBad())
  19.             throw std::logic_error("some error message goes here\n");
  20.         return;
  21.     }
  22.     SpaceWaster next(current->level - 1,  current->isBad(), current);
  23.     // typical exception-using code doesn't need error return values
  24.     thrower(&next);
  25.     thrower(&next);
  26.     thrower(&next);
  27.     return;
  28. }
  29.  
  30. char const*     errorMsg;
  31.  
  32. char const*     errorMsg;
  33.  
  34. int returner(SpaceWaster *current) {
  35.     if (current->checkLevel())
  36.     {
  37.         if (current->isBad())
  38.         {
  39.             errorMsg    = "some error message goes here\n:";
  40.             return -1;
  41.         }
  42.         return 0;
  43.     }
  44.     SpaceWaster next(current->level - 1, current->isBad(), current);
  45.     // typical exception-free code requires that return values be handled
  46.     int result = returner(&next);
  47.     if (result == 0)
  48.     {
  49.         result  = returner(&next);
  50.     }
  51.     if (result == 0)
  52.     {
  53.         result  = returner(&next);
  54.     }
  55.     return result;
  56. }
  57.  
  58. int main()
  59. {
  60.     const int repeats = 1000;
  61.     int returns = 0;
  62.     int fails   = 0;
  63.  
  64.     for (int i = 0; i < repeats; ++i)
  65.     {
  66.         SpaceWaster first(10, (i%100) == 0, 0);
  67. #ifdef THROW
  68.         try
  69.         {
  70.             thrower(&first);
  71.             ++returns;
  72.         }
  73.         catch (std::exception &e)
  74.         {
  75.             ++fails;
  76.         }
  77. #else
  78.         if (returner(&first) == 0)
  79.         {
  80.             ++returns;
  81.         }
  82.         else
  83.         {
  84.             ++fails;
  85.         }
  86. #endif
  87.     }
  88.     std::cout << fails << ":" << returns
  89. #ifdef THROW
  90.     << " exceptions"
  91. #else
  92.     << " returns"
  93. #endif
  94.     << "\n";
  95. }
  96.  
  97. [Alpha:~] myork% g++ -DTHROW t.cpp
  98. [Alpha:~] myork% time ./a.out
  99. 10:990 exceptions
  100. 1.275u 0.001s 0:01.27 100.0%	0+0k 0+0io 0pf+0w
  101.  
  102.  
  103. [Alpha:~] myork% g++  t.cpp
  104. [Alpha:~] myork% time ./a.out
  105. 10:990 returns
  106. 1.325u 0.003s 0:01.33 99.2%	0+0k 0+0io 0pf+0w

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