Adding folding expressions example

Author: harris2001

C++17/CMakeLists.txt

@@ -0,0 +1,12 @@
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+file(GLOB CPP_FILES "*.cpp")
+
+foreach(CPP_FILE ${CPP_FILES})
+	get_filename_component(TARGET_NAME ${CPP_FILE} NAME_WE)
+
+	add_executable(${TARGET_NAME} ${CPP_FILE})
+
+	add_test(NAME ${TARGET_NAME} COMMAND ${TARGET_NAME})
+endforeach()

C++17/fold_expressions.cpp

@@ -0,0 +1,34 @@
+//#include <print> // Needs to be included if we are using C++23 print function
+#include <iostream>
+#include <vector>
+#include <set>
+#include <string>
+
+//size_t... I is a std::integer_sequence whose values are specified by a non-type template
+template<typename TupleT, size_t... IdxT>
+void print(const TupleT& tupl, std::index_sequence<IdxT...>){
+	//This experssion (..., operator) folds the tuple by applying operator to
+	// each of its elements going from left to right
+	std::cout << "(";
+	(..., (std::cout << (IdxT == 0 ? "" : ", ") << std::get<IdxT>(tupl)));
+	std::cout << ")\n";
+}
+
+// This is a non-type template that takes a tuple with multiple arguments of some type T
+template<typename... T>
+void printTuple(const std::tuple<T...>& tupl){
+	//std::make_integer_sequence creates a sequence of integers of size equal to the number of arguments of T 
+	print(tupl, std::make_index_sequence<sizeof...(T)>());
+}	
+
+int main(){
+	std::vector<std::tuple<std::string>> my_list = {("5","3","1"),("1","3","2"),("3","5","A"),("6","4","5")};
+
+	auto a = std::make_index_sequence<4>();
+	for(auto tupl_ : my_list){
+		//std::cout << std::fmt("{}", my_list[i]) << std::endl; //For C++20 use format
+		//print("{}", my_list[i]); // For C++23 use print
+		printTuple(tupl_);
+	}
+	return 0;
+}

CMakeLists.txt

@@ -4,6 +4,7 @@ project(CppExamples LANGUAGES CXX)
 enable_testing()
 
 set(SUBDIRS C++11)
+set(SUBDIRS C++17)
 
 foreach(SUBDIR ${SUBDIRS})
     add_subdirectory(${SUBDIR})