prepare for c++17

code/3/3.1.cpp

@@ -0,0 +1,52 @@
+//
+// 3.1.cpp
+// c++1x tutorial
+//
+// created by changkun at shiyanlou.com
+//
+// lambda expression
+
+#include <iostream>
+#include <utility>
+
+void learn_lambda_func_1() {
+    int value_1 = 1;
+    auto copy_value_1 = [value_1] {
+        return value_1;
+    };
+    value_1 = 100;
+    auto stored_value_1 = copy_value_1();
+    // 这时, stored_value_1 == 1, 而 value_1 == 100.
+    // 因为 copy_value_1 在创建时就保存了一份 value_1 的拷贝
+}
+
+void learn_lambda_func_2() {
+    int value_2 = 1;
+    auto copy_value_2 = [&value_2] {
+        return value_2;
+    };
+    value_2 = 100;
+    auto stored_value_2 = copy_value_2();
+    // 这时, stored_value_2 == 100, value_1 == 100.
+    // 因为 copy_value_2 保存的是引用
+}
+
+int main() {
+    learn_lambda_func_1();
+    learn_lambda_func_2();
+    
+    auto important = std::make_unique<int>(1);
+    auto add = [v1 = 1, v2 = std::move(important)](int x, int y) -> int {
+        return x+y+v1+(*v2);
+    };
+    std::cout << add(3,4) << std::endl;
+    
+    // 泛型 lambda
+    auto generic = [](auto x, auto y) {
+        return x+y;
+    };
+    
+    generic(1, 2);
+    generic(1.1, 2.2);
+    return 0;
+}