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

44 lines
2.0 KiB
C++

// 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>
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{1, 6};
constexpr size_t arraySize{7}; // ignore element zero
std::array<int, arraySize> frequency{}; // initialize to 0s
// roll die 60,000,000 times; use die value as frequency index
for (int roll{1}; roll <= 60'000'000; ++roll) {
++frequency.at(randomDie(engine));
}
std::cout << std::format("{}{:>13}\n", "Face", "Frequency");
// output each array element's value
for (size_t face{1}; face < frequency.size(); ++face) {
std::cout << std::format("{:>4}{:>13}\n", face, frequency.at(face));
}
}
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