#include using namespace std; /* No input, description is in the output. */ class var { public: template void set(A val) { A * a = new A(); *a = val; s = sizeof(A); if (p != NULL) { delete p; } p = a; } template A get(int i = 0) { return *((A*)(p + (i * sizeof(A)))); } int size() { return s; } private: void * p = NULL; int s = 0; }; class li { public: void resize(int size) { if (v == NULL) { v = new var[size]; count = size; } else { var * tv = new var[count]; for (int a=0; a < count; a++) { *(tv + a) = *(v + a); } delete v; v = new var[size]; for (int a=0; a < count && a < size; a++) { *(v + a) = *(tv + a); } count = size; } } var &operator[](int a) { return v[a]; } int size() { int res = 0; for (int a = 0; a < count; a++) { res += (v + a)->size(); } return res; } private: var * v = NULL; int count = 0; }; int main() { cout << "This code shows how void* can be used to create a dynamically typed class. For each type, there will be the following output:\n\nTYPE NAME\nVALUE\nSIZE\n\n"; cout << "Size of var class: " << sizeof(var) << "\n\n"; var v; cout << "INT" << endl; v.set(5); cout << v.get() << endl; cout << v.size() << endl << endl; cout << "FLOAT" << endl; v.set(3.14f); cout << v.get() << endl; cout << v.size() << endl << endl; cout << "DOUBLE" << endl; v.set(3.1415926); cout << v.get() << endl; cout << v.size() << endl << endl; cout << "BOOL" << endl; v.set(true); cout << v.get() << endl; cout << v.size() << endl << endl; cout << "CHAR" << endl; v.set('W'); cout << v.get() << endl; cout << v.size() << endl << endl; cout << "STRING" << endl; v.set("Hello!"); cout << v.get() << endl; cout << v.size() << endl << endl; cout << "Now, as a dynamically typed data type, how do lists work?\n\nSize of list: " << sizeof(li) << "\n\n"; li myList; myList.resize(1); myList[0].set(2); cout << "[" << myList[0].get() << "]" << endl; cout << "SIZE: " << myList.size() << "\n\n"; myList.resize(2); myList[1].set(3.14f * 2); cout << "[" << myList[0].get() << ", " << myList[1].get() << "]" << endl; cout << "SIZE: " << myList.size() << "\n\n"; myList.resize(3); myList[2].set(3.1415926 * 2); cout << "[" << myList[0].get() << ", " << myList[1].get() << ", " << myList[2].get() << "]" << endl; cout << "SIZE: " << myList.size() << "\n\n"; myList.resize(4); myList[3].set(false); cout << "[" << myList[0].get() << ", " << myList[1].get() << ", " << myList[2].get() << ", " << myList[3].get() << "]" << endl; cout << "SIZE: " << myList.size() << "\n\n"; myList.resize(5); myList[4].set('$'); cout << "[" << myList[0].get() << ", " << myList[1].get() << ", " << myList[2].get() << ", " << myList[3].get() << ", " << myList[4].get() << "]" << endl; cout << "SIZE: " << myList.size() << "\n\n"; myList.resize(6); myList[5].set("HI!!!"); cout << "[" << myList[0].get() << ", " << myList[1].get() << ", " << myList[2].get() << ", " << myList[3].get() << ", " << myList[4].get() << ", " << myList[5].get() << "]" << endl; cout << "SIZE: " << myList.size() << "\n\n"; cout << "Only one object was actually created in the main function. That object was used to hold all of these values. It can also hold any user-defined class because it uses a void* instead of a separate pointer for each type.\n\nNow just for fun, what happens when I try to access an integer value as a float value?\n\n"; v.set(44); cout << v.get() << "\n\nThat output was with the following code:\n\nv.set(44);\ncout << v.get();"; return 0; }

Dynamically Typed