add Chapter08

Chapter08/tmpt_concepts.cpp

@@ -0,0 +1,44 @@
+#include <cstdio>
+#include <type_traits>
+
+struct point { 
+    int x; 
+    int y; 
+
+    point operator+(const point& other) const { 
+        return point{x + other.x, y + other.y}; 
+    } 
+
+    void print() { 
+        printf("x = %d, y = %d\r\n", x, y); 
+    } 
+}; 
+
+template<typename T> 
+concept Arithmetic = std::is_arithmetic_v<T>; 
+
+
+template<Arithmetic T> 
+T add(T a, T b) { 
+
+    T result = a + b; 
+    if constexpr (std::is_integral_v<T>) { 
+        printf("%d + %d = %d\r\n", a, b, result); 
+    } else if constexpr (std::is_floating_point_v<T>) { 
+        printf("%.2f + %.2f = %.2f\r\n", a, b, result); 
+    } 
+
+    return a + b;  
+} 
+
+int main() { 
+
+    auto a = add(1, 2); // OK 
+    auto b = add(1.1, 2.1); // OK 
+
+    point p_a{1, 2};  
+    point p_b{2, 1};   
+    auto c = add(p_a, p_b); // compile-error 
+
+    return 0; 
+}