C++11 function函数用法

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80

// C++11 function #include <functional> void print_num(int i) {     std::cout << i << '\n'; } void testFunctionTpl() {     // templet 匿名函数     std::function<void(const int&, const int&)>getSum = [&](const int &nI1, const int &nI2)     {         int nSum = nI1 + nI2;         std::cout << nSum << endl;     };      getSum(8, 9);        //  lambda      std::function<void()> f_display_42 = []() { print_num(42); };      f_display_42();          //********************* 测试成员函数 begin*********************//      class TestClass      {      public:          TestClass(int i) : m_nI(i){}          ~TestClass() {}          void testMemberFunc(int i) const { std::cout << m_nI + i << endl; }          int  testResultFun(int i) const { return m_nI + i; }          void testBindFun(int num) const { std::cout << m_nI + num << endl; }          int m_nI;      };               std::function<void(const TestClass&, int)> testMemberFunc = &TestClass::testMemberFunc;      const TestClass oTestObject(100);      // 传对象      testMemberFunc(oTestObject, 100);      // 会根据模板构造对象      testMemberFunc(300, 100);      //  返回值成员函数      std::function<int(const TestClass&, int)> testResultFun = &TestClass::testResultFun;      int nRet = testResultFun(oTestObject, 100);      std::cout << nRet << endl;      // 成员变量      std::function<int(const TestClass&)> f_num = &TestClass::m_nI;      std::cout << "m_nI: " << f_num(oTestObject) << '\n';        // 对象形式调用成员函数      using std::placeholders::_1; // 占位符      std::function<void(int)> testBindFun = std::bind(&TestClass::testBindFun, oTestObject, _1);      testBindFun(222);        // 指针形式调用成员函数      std::function<void(int)> testBindFun2 = std::bind(&TestClass::testBindFun, &oTestObject, _1);      testBindFun2(333);      //********************* 测试成员函数 end*********************//        //********************* 测试普通函数 begin*********************//        // 绑定普通函数      std::function<void()> f_display_31337 = std::bind(print_num, 31337);      f_display_31337();      //********************* 测试普通函数 end*********************//        // bad_function_call      std::function<int()> f = nullptr;      try {          f();      }      catch (const std::bad_function_call& e) {          std::cout << e.what() << '\n';      }        } int main() {     testFunctionTpl();     int i = 0; }