Update notes on template

Author: XuhuaHuang

Template/ClassTemplate/calc.cpp

@@ -0,0 +1,23 @@
+#include <iostream>
+
+template <typename T>
+class calc_t {
+public:
+  [[nodiscard]]
+  constexpr T multiply(T x, T y) const noexcept {
+    return x * y;
+  }
+
+  [[nodiscard]]
+  constexpr T add(T x, T y) const noexcept {
+    return x + y;
+  }
+};
+
+int main() {
+  calc_t<int> c;
+
+  std::cout << c.add(10, 20) << std::endl;
+
+  return 0;
+}

Template/FunctionTemplate/main.cpp

@@ -1,23 +1,25 @@
+// clang-format off
 /*****************************************************************//**
  * \file   main.cpp
  * \brief
  *
  * \author Xuhua Huang
  * \date   November 15, 2022
  *********************************************************************/
+// clang-format on
 
 #include <iostream>
 
 #include "max.hpp"
 
 int main(void) {
-    // implicit template instanciation
-    // T is deducted to int
-    // same for std::vector
-    // std::vector v { 1, 2 };
-    // std::cout << max<int>(42, 77) << "\n";
-    std::cout << max(42, 77) << "\n";
-    std::cout << max<double>(3.14, 3.1415) << "\n";
+  // implicit template instanciation
+  // T is deducted to int
+  // same for std::vector
+  // std::vector v { 1, 2 };
+  // std::cout << max<int>(42, 77) << "\n";
+  std::cout << max(42, 77) << "\n";
+  std::cout << max<double>(3.14, 3.1415) << "\n";
 
-    return EXIT_SUCCESS;
+  return 0;
 }

Template/FunctionTemplate/max.hpp

@@ -1,19 +1,17 @@
+// clang-format off
 /*****************************************************************//**
- * \file   main.hpp
+ * \file   max.hpp
  * \brief  Usually the definition of a templated function is provided
  * in the same header file, instead of a separate translation unit.
  *
  * \author Xuhua Huang
  * \date   November 15, 2022
  *********************************************************************/
+// clang-format on
 
 #ifndef MAX_HPP
 #define MAX_HPP
 
-#ifndef _IOSTREAM_
-#include <iostream>
-#endif
-
 #include <concepts>
 
 /**
@@ -31,9 +29,21 @@ concept SupportsLessThan = requires (T t) { t < t; };
 
 /* Adding explicit constraint for T */
 template <typename T>
-    requires std::copyable<T> && SupportsLessThan<T>
+  requires std::copyable<T> && SupportsLessThan<T>
 T max(T a, T b) {
-    return b < a ? a : b;
+  return b < a ? a : b;
+}
+
+/** \brief Returns the maximum of two values.
+ *  \tparam T The type of the values.
+ *  \param a The first value.
+ *  \param b The second value.
+ *  \return The maximum of a and b.
+ */
+template <typename T>
+[[nodiscard]]
+constexpr T maximum(T a, T b) noexcept {
+  return (a > b) ? a : b;
 }
 
 #endif