C++ generic function pointer example / use (void*) as object pointer

 #include "stdafx.h"  
 #include <iostream>  
 #include <functional>  
 using namespace std;  
 class Point  
 {  
 public:  
      Point(double _x, double _y) :x(_x), y(_y) {};  
      double x;  
      double y;  
 };  
 typedef std::function<void*(void*)> genericFunc;  
 void * func1(void * argv) {  
      double * d = (double *)argv;  
      double x = d[0];  
      double y = d[1];  
      Point p(x, y);  
      Point* pp = &p;  
      return (void *)pp;  
 }  
 void * func2(void * argv) {  
      double * d = (double *)argv;  
      double x = d[0];  
      double y = d[1];  
      double z = d[2];  
      double R = x * y * z;  
      return (void *)&R;  
 }  
 void * TestFunc(genericFunc f, void* p)  
 {  
      return f(p);  
 }  
 int main()  
 {  
      double argv[]{ 1.2, 2.3, 3.4 };  
      Point p = * ( (Point*) TestFunc(&func1, (void*)argv) );  
      double d = *((double*)TestFunc(&func2, (void*)argv));  
      cout << "p:" << p.x << "," << p.y << ", d:" << d << endl;  
      getchar();  
   return 0;  
 }  

C++ pass member function pointer as function parameter example

 #include "stdafx.h"  
 #include <vector>  
 #include <iostream>  
 #include <functional>  
 #include <vector>  
 #include <string>  
 using namespace std;  
 typedef std::function<double(int, int)> funcIntToDouble;  
 class parent;  
 class child  
 {  
 public:  
      double childValue;  
      child()  
      {  
           childValue = 10.5;  
      }  
      double InChildFunc(funcIntToDouble f, int x, int i)  
      {  
           double d = f(x, i) + childValue;  
           cout << endl << "InChildFunc: " << d << endl;  
           return d;  
      }  
 };  
 class parent  
 {  
 public:  
      int y;  
      child childObject;  
      vector<double> vec{ 1.1, 2.2, 3.3 };  
      parent()  
      {  
           y = 10.0;  
      }  
      double ParentFunc(int x, int i)  
      {  
           double d = (double)x * y + vec[i];  
           return d;  
      }  
      void CallChildObject(int parentX, int parentI)  
      {  
           funcIntToDouble f = [&](int x, int i) {  
                double d = ParentFunc(x, i);  
                return d;  
           };  
           double r = childObject.InChildFunc(f, parentX, parentI);  
           cout << endl << "CallChildObject: " << r << endl;  
      }  
 };  
 int main()  
 {  
      parent p;  
      p.CallChildObject(10, 1);  
      getchar();  
      return 0;  
 }  

C++ passing vector as shared_ptr example

 #include <functional>  
 using namespace std;  
 void Test(shared_ptr<vector<int>> v)  
 {  
      vector<int> & r_v = *(v.get());  
      cout << r_v[1];  
 }  
 int main()  
 {  
      shared_ptr<vector<int>> a = make_shared<vector<int>>(std::vector<int>{ 1, 2, 3 });  
      Test(a);  
      getchar();  
      return 0;  
 }  

Function Pointer Object example in C++

 using namespace std;  
 typedef std::function<double(int)> funcIntToDouble;  
 void Test(funcIntToDouble f, int x)  
 {  
      double b = f(x);  
      cout << b;  
 }  
 int main()  
 {  
      cout << "function object example" << endl;  
      int a = 10;  
      funcIntToDouble f = [&](int x) {  
           double r = (double)(x + a) / 10; //able use use variable a from the calling function  
           return r;  
      };  
      Test(f, 15); //pass the function pointer along with value from variables in scope  
      getchar();  
   return 0;  
 }