c-resources/CPlusPlus20ForProgrammers-m.../examples/ch15/fig15_16.cpp

59 lines
2.4 KiB
C++

// fig15_16.cpp
// Binary fold expressions.
#include <fmt/format.h>
#include <iostream>
template <typename... Items>
auto binaryLeftAdd(Items... items) {
return (0 + ... + items); // binary left fold
}
template <typename... Items>
auto binaryRightAdd(Items... items) {
return (items + ... + 0); // binary right fold
}
template <typename... Items>
auto binaryLeftSubtract(Items... items) {
return (0 - ... - items); // binary left fold
}
template <typename... Items>
auto binaryRightSubtract(Items... items) {
return (items - ... - 0); // binary right fold
}
int main() {
std::cout << "Binary left and right fold with addition:"
<< fmt::format("\n{}{}\n{}{}\n{}{}\n{}{}\n\n",
"binaryLeftAdd(): ", binaryLeftAdd(),
"binaryLeftAdd(1, 2, 3, 4): ", binaryLeftAdd(1, 2, 3, 4),
"binaryRightAdd(): ", binaryRightAdd(),
"binaryRightAdd(1, 2, 3, 4): ", binaryRightAdd(1, 2, 3, 4));
std::cout << "Binary left and right fold with subtraction:"
<< fmt::format("\n{}{}\n{}{}\n{}{}\n{}{}\n",
"binaryLeftSubtract(): ", binaryLeftSubtract(),
"binaryLeftSubtract(1, 2, 3, 4): ",
binaryLeftSubtract(1, 2, 3, 4),
"binaryRightSubtract(): ", binaryRightSubtract(),
"binaryRightSubtract(1, 2, 3, 4): ",
binaryRightSubtract(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 *
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* 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 *
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* furnishing, performance, or use of these programs. *
**************************************************************************/