c++functional

c++/functional/main.cpp

+#include <iostream>
+#include <functional>
+
+int print(int a){
+  std::cout << a << std::endl;
+  return 0;
+}
+
+int print_sum(int a, int b, int c){
+  std::cout << a+b+c << std::endl;
+  return 0;
+}
+
+class classA {
+public:
+  void testPrint(int a){
+    std::cout << a << std::endl;
+  }
+};
+
+int main(){
+  std::function<int(int)> func1(print);
+  func1(11);
+
+  std::function<int(int)> func2([](int a) { std::cout << a << std::endl; return 0; }); // 2
+  func2(22);
+
+  std::function<int(int)> func3 = std::bind(print, std::placeholders::_1);
+  func3(33);
+
+  classA cla;
+  std::function<void(int)> func4 = std::bind(&classA::testPrint, &cla, std::placeholders::_1);
+  func4(44);
+
+  std::function<int(int, int)> func5 = std::bind(print_sum, 1, std::placeholders::_1, std::placeholders::_2);
+  func5(55, 1);
+
+  return 0;
+}