ADD file via upload

Date.cpp

@@ -0,0 +1,13 @@
+#include "Date.h"
+
+Date::Date(int year, int month, int day)
+{
+    this->year = year;
+    this->month = month;
+    this->day = day;
+}
+
+string Date::ShowDate()
+{
+    return to_string(this->year) + "-" + to_string(this->month) + "-" + to_string(this->day);
+}