feat: test decltype

chapters/chapter_02/src/type_inference.cpp

@@ -1,7 +1,31 @@
 #include "type_inference.h"
 #include <iostream>
+#include <type_traits>
 #include <vector>
 
+auto print_sum(auto x, auto y) {
+
+  decltype(x + y) sum = x + y;
+
+  std::cout << "sum is " << sum << std::endl;
+
+  return sum;
+}
+
+void print_decltype(auto var) {
+  std::cout << "variable with value " << var << " is of type ";
+
+  if (std::is_same<decltype(var), int>::value) {
+    std::cout << "int";
+  } else if (std::is_same<decltype(var), double>::value) {
+    std::cout << "double";
+  } else {
+    std::cout << "unknown";
+  }
+
+  std::cout << std::endl;
+}
+
 void TypeInferenceTest::run() {
 
   const std::vector<int> int_vec = {1, 2, 3, 4, 5};
@@ -11,4 +35,12 @@ void TypeInferenceTest::run() {
     std::cout << *it << " ";
   }
   std::cout << std::endl;
+
+  auto result_1 = print_sum(10.2, 13.3);
+  print_decltype(result_1);
+
+  auto result_2 = print_sum(10, 13);
+  print_decltype(result_2);
+
+  print_decltype("23");
 }