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  1. #include <iostream>
  2. #include <iomanip>
  3.  
  4. struct tabber
  5. {
  6.     static unsigned width;
  7.     static unsigned increment;
  8.  
  9.     unsigned increments = 0;
  10.  
  11.     tabber() : increments(0) { }
  12.     tabber(const tabber&) = delete;
  13.  
  14.     tabber(unsigned count) : increments(count) { width += increment * increments; }
  15.     ~tabber() { width -= increments * increment; }
  16.  
  17.     tabber& operator=(const tabber&) = delete;
  18.  
  19.     tabber& inc() { ++increments; width += increment; return *this; }
  20.     tabber& dec() { if (increments) { --increments; width -= increment; } return *this; }
  21. };
  22.  
  23. unsigned tabber::width = 0;
  24. unsigned tabber::increment = 3;
  25.  
  26. std::ostream& operator<<(std::ostream& os, const tabber& tab)
  27. {
  28.     if ( tabber::width )
  29.         os << std::setw(tabber::width) << ' ';
  30.  
  31.     return os;
  32. }
  33.  
  34.  
  35. float return_value(tabber& t, float value)
  36. {
  37.     std::cout << t.dec() << value << '\n';
  38.     return value;
  39. }
  40.  
  41. float pow(int base, int power)
  42. {
  43.     tabber t;
  44.     std::cout << t << "pow(" << base << ", " << power << ")\n";
  45.     t.inc();
  46.  
  47.     if (power == 0)
  48.         return return_value(t, 1.0);
  49.  
  50.     if (power == 1)
  51.         return return_value(t, base);
  52.  
  53.     if (base < 0)
  54.     {
  55.         std::cout << t << "base is negative - recalling with positive base.\n";
  56.         return return_value(t, pow(-base, power));
  57.     }
  58.  
  59.     if (power < 0)
  60.     {
  61.         std::cout << t << "power is negative - recalling with positive power.\n";
  62.         float value = 1.0 / pow(base, -power);
  63.  
  64.         std::cout << t << "Since power was negative, dividing 1.0 by return value.\n";
  65.         return return_value(t, value);
  66.     }
  67.  
  68.     return return_value(t, base * pow(base, power - 1));
  69. }
  70.  
  71. int main()
  72. {
  73.     int base = 2; 
  74.     int power = -3;
  75.  
  76.     pow(base, power);
  77. }
Success #stdin #stdout 0s 3340KB
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Standard input is empty
stdout
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pow(2, -3)
   power is negative - recalling with positive power.
   pow(2, 3)
      pow(2, 2)
         pow(2, 1)
         2
      4
   8
   Since power was negative, dividing 1.0 by return value.
0.125
https://ideone.com/jJGECz
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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