2017.2.18

  1 //函数包装器， T数据类型， F是函数
  2 template<typename T,typename F>
  3 T run(T v, F f)
  4 {
  5 	static int count = 0;
  6 	count++;//计数器
  7 	std::cout << "run  一个参数的包装器 执行" << count << "次" << std::endl;
  8 	if (count > 1)
  9 	{
 10 		T  vx(0);
 11 		return  vx;
 12 	}
 13 	return f(v);//函数传入参数
 14 }
 15 int  cheng(int a, int b)
 16 {
 17 	return a*b;
 18 }
 19 
 20 int  main()
 21 {
 22         function<double(double)> fun1 = [](double u)
 23 	{
 24 		return u * 2;
 25 	};
 26 	function<double(double)> fun2 = [](double u)
 27 	{
 28 		return u*u;
 29 	};
 30 	function<int(int, int)> fun3 = [](int u1,int u2)
 31 	{
 32 		return u1 + u2;
 33 	};
 34 	function<int(int, int)> fun4 = cheng; //fun4函数指针
 35 }