93 lines
3.0 KiB
C++
93 lines
3.0 KiB
C++
// fig06_12.cpp
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// Compute the product of an array's elements using accumulate.
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#include <array>
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#include <iostream>
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#include <numeric>
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template <typename T>
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T multiply(T x, T y) {
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return x * y;
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}
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int multiply_int(int x, int y) {
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return x * y;
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}
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double f(double& x){
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return x*x;
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}
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template <typename T, typename F, long unsigned int N>
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T integrate (std::array<T, N> x, F f){
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T tmp{T(0)};
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for (auto s: x){
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tmp+= f(s);
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}
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return tmp;
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}
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typedef double (*FUNC)(double&);
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template <typename T, long unsigned int N>
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T integrate2 (std::array<T, N> x, FUNC f){
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T tmp{T(0)};
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for (auto s: x){
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tmp+= f(s);
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}
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return tmp;
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}
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int main() {
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constexpr std::array integers{1, 2, 3, 4, 5};
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std::array floats {1.0, 2.0, 3.0, 4.0, 5.0};
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auto multiply_lambda = [](const auto& x, const auto& y) {return x * y; };
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auto f_lambda = [](auto& x) {return x*x;};
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auto g_lambda = [&integers](auto& x) {
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auto tmp{0};
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for (int i{0};auto s: x){
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tmp += s*integers[i];
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}
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return tmp;
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};
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std::cout << "Product of integers: " << std::accumulate( std::begin(integers), std::end(integers), 1, multiply<int>) << "\n";
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std::cout << "Product of integers: " << std::accumulate( integers.cbegin(), integers.cend(), 1, multiply<int>) << "\n";
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std::cout << "Product of integers with a lambda: " << std::accumulate(std::begin(integers), std::end(integers), 1, multiply_lambda) << "\n";
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std::cout << "Product of integers with a lambda: " << std::accumulate(std::begin(floats), std::end(floats), 1, multiply_int) << "\n";
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std::cout << "Product of integers with a lambda: " << std::accumulate(std::begin(floats), std::end(floats), 1, multiply_lambda) << "\n";
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std::cout << "Integration2 template " << integrate2(floats, f) << "\n";
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std::cout << "Integration full template " << integrate(floats, f_lambda) << "\n";
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std::cout << "Lambda test " << g_lambda(floats) << "\n";
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}
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/**************************************************************************
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* (C) Copyright 1992-2022 by Deitel & Associates, Inc. and *
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* Pearson Education, Inc. All Rights Reserved. *
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* *
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* DISCLAIMER: The authors and publisher of this book have used their *
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* best efforts in preparing the book. These efforts include the *
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* development, research, and testing of the theories and programs *
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* to determine their effectiveness. The authors and publisher make *
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* no warranty of any kind, expressed or implied, with regard to these *
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* programs or to the documentation contained in these books. The authors *
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* and publisher shall not be liable in any event for incidental or *
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* consequential damages in connection with, or arising out of, the *
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* furnishing, performance, or use of these programs. *
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**************************************************************************/
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