Data update

Task/History-variables/C++/history-variables.cpp

@@ -0,0 +1,60 @@
+#include <deque>
+#include <iostream>
+#include <string>
+
+template <typename T>
+class with_history {
+public:
+	with_history(const T& element) {
+		history.push_front(element);
+	}
+
+	T get() {
+		return history.front();
+	}
+
+	void set(const T& element) {
+		history.push_front(element);
+	}
+
+	std::deque<T> get_history() {
+		return std::deque<T>(history);
+	}
+
+	T rollback() {
+		if ( history.size() > 1 ) {
+			history.pop_front();
+		}
+		return history.front();
+	}
+
+private:
+	std::deque<T> history;
+};
+
+int main() {
+	with_history<double> number(1.2345);
+	std::cout << "Current value of number: " << number.get() << std::endl;
+
+	number.set(3.4567);
+	number.set(5.6789);
+
+	std::cout << "Historical values of number: ";
+	for ( const double& value : number.get_history() ) {
+		std::cout << value << "  ";
+	}
+	std::cout << std::endl << std::endl;
+
+	with_history<std::string> word("Goodbye");
+	word.set("Farewell");
+	word.set("Hello");
+
+	std::cout << word.get() << std::endl;
+	word.rollback();
+	std::cout << word.get() << std::endl;
+	word.rollback();
+	std::cout << word.get() << std::endl;
+	word.rollback();
+	std::cout << word.get() << std::endl;
+	word.rollback();
+}