c-resources/CPlusPlus20ForProgrammers-m.../examples/ch15/fig15_15.cpp

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// fig15_15.cpp
// Unary fold expressions.
#include <fmt/format.h>
#include <iostream>
template <typename... Items>
auto unaryLeftAdd(Items... items) {
return (... + items); // unary left fold
}
template <typename... Items>
auto unaryRightAdd(Items... items) {
return (items + ...); // unary right fold
}
template <typename... Items>
auto unaryLeftSubtract(Items... items) {
return (... - items); // unary left fold
}
template <typename... Items>
auto unaryRightSubtract(Items... items) {
return (items - ...); // unary right fold
}
int main() {
std::cout << "Unary left and right fold with addition:"
<< fmt::format("\n{}{}\n{}{}\n\n",
"unaryLeftAdd(1, 2, 3, 4): ", unaryLeftAdd(1, 2, 3, 4),
"unaryRightAdd(1, 2, 3, 4): ", unaryRightAdd(1, 2, 3, 4));
std::cout << "Unary left and right fold with subtraction:"
<< fmt::format("\n{}{}\n{}{}\n",
"unaryLeftSubtract(1, 2, 3, 4): ",
unaryLeftSubtract(1, 2, 3, 4),
"unaryRightSubtract(1, 2, 3, 4): ",
unaryRightSubtract(1, 2, 3, 4));
}
/**************************************************************************
* (C) Copyright 1992-2022 by Deitel & Associates, Inc. and *
* Pearson Education, Inc. All Rights Reserved. *
* *
* DISCLAIMER: The authors and publisher of this book have used their *
* best efforts in preparing the book. These efforts include the *
* development, research, and testing of the theories and programs *
* to determine their effectiveness. The authors and publisher make *
* no warranty of any kind, expressed or implied, with regard to these *
* programs or to the documentation contained in these books. The authors *
* and publisher shall not be liable in any event for incidental or *
* consequential damages in connection with, or arising out of, the *
* furnishing, performance, or use of these programs. *
**************************************************************************/