c-resources/CPlusPlus20ForProgrammers-master/examples/ch06/fig06_07.cpp

// fig06_07.cpp
// Die-rolling program using an array instead of switch.
//#include <format> // C++20: This will be #include <format>
#include <iostream>
#include <array>
#include <random>

template <int N>
void accumulate(std::array<double, N>& histogram, double val, double upper, double lower){

	double del {(upper-lower)/N};
	for (int i{0}; i < N; i++){
		if ( val > i*del && val < (i+1) * del )
			histogram[i]++;
	}
	return;
}

int main() {
   // set up random-number generation
   std::random_device rd; // used to seed the default_random_engine
   std::default_random_engine engine{rd()}; // rd() produces a seed 
   std::uniform_int_distribution randomDie{0, 6};

   double upper_bound = 1;
   std::uniform_real_distribution<double> randomReal{0, upper_bound};

   constexpr size_t arraySize{7}; // ignore element zero
   std::array<int, arraySize> frequency{}; // initialize to 0s


   constexpr size_t N{7};
   std::array<double, N> histogram{};

   // roll die 60,000,000 times; use die value as frequency index
   for (int roll{1}; roll <= 60'000'000; ++roll) {
	   frequency[roll]++;
//       randomReal(engine);
   }


   std::cout <<  "Face " <<  " Frequency  \n";

   // output each array element's value
   for (size_t face{1}; face < histogram.size(); ++face) {
      std::cout << face << " " << histogram.at(face) << "\n";
   }
}

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