// pointers.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
#include <string>

class MyClass
{
public:
    int num;
    std::string name;
    void print() { std::cout << name << ":" << num << std::endl; }
};

// Accepts a MyClass pointer
void func_A(MyClass* mc)
{
    // Modify the object that mc points to.
    // All copies of the pointer will point to
    // the same modified object.
    mc->num = 3;
}

// Accepts a MyClass object
void func_B(MyClass mc)
{
    // mc here is a regular object, not a pointer.
    // Use the "." operator to access members.
    // This statement modifies only the local copy of mc.
    mc.num = 21;
    std::cout << "Local copy of mc:";
    mc.print(); // "Lisa, 21"
}


int main()
{
    // Use the * operator to declare a pointer type
    // Use new to allocate and initialize memory
    MyClass* mc = new MyClass{ 108, "Mike" };

    // Prints the memory address. Usually not what you want.
   // std:: cout << mc << std::endl;

    // Use the -> operator to access the object's public members
    mc->print(); // "Mike, 108"

    // Copy the pointer. Now mc and mc2 point to same object!
    MyClass* mc2 = mc;

    // Use copied pointer to modify the original object
    mc2->name = "Lisa";
    mc->print(); // "Lisa, 108"
    mc2->print(); // "Lisa, 108"

    // Pass the pointer to a function.
    func_A(mc);
    mc->print(); // "Lisa, 3"
    mc2->print(); // "Lisa, 3"

    // Dereference the pointer and pass a copy
    // of the pointed-to object to a function
    func_B(*mc);
    mc->print(); // "Lisa, 3" (original not modified by function)

    delete(mc); // don't forget to give memory back to operating system!
   // delete(mc2); //crash! memory location was already deleted
}

char *pch;

static unsigned int * const ptr;

static int *p = &i, *q = &j;

// pointer.cpp
// compile with: /EHsc
#include <iostream>
int main() {
   int i = 1, j = 2; // local variables on the stack
   int *p;

   // a pointer may be assigned to "point to" the value of
   // another variable using the & (address of) operator
   p = & j;

   // since j was on the stack, this address will be somewhere
   // on the stack.  Pointers are printed in hex format using
   // %p and conventionally marked with 0x.
   printf_s("0x%p\n",  p);

   // The * (indirection operator) can be read as "the value
   // pointed to by".
   // Since p is pointing to j, this should print "2"
   printf_s("0x%p %d\n",  p, *p);

   // changing j will change the result of the indirection
   // operator on p.
   j = 7;
   printf_s("0x%p %d\n",  p, *p );

   // The value of j can also be changed through the pointer
   // by making an assignment to the dereferenced pointer
   *p = 10;
   printf_s("j is %d\n", j); // j is now 10

   // allocate memory on the heap for an integer,
   // initialize to 5
   p = new int(5);

   // print the pointer and the object pointed to
   // the address will be somewhere on the heap
   printf_s("0x%p %d\n",  p, *p);

   // free the memory pointed to by p
   delete p;

   // At this point, dereferencing p with *p would trigger
   // a runtime access violation.

   // Pointer arithmetic may be done with an array declared
   // on the stack or allocated on the heap with new.
   // The increment operator takes into account the size
   // of the objects pointed to.
   p = new int[5];
   for (i = 0; i < 5; i++, p++) {
      *p = i * 10;
      printf_s("0x%p %d\n", p, *p);
   }

   // A common expression seen is dereferencing in combination
   // with increment or decrement operators, as shown here.
   // The indirection operator * takes precedence over the
   // increment operator ++.
   // These are particularly useful in manipulating char arrays.
   char s1[4] = "cat";
   char s2[4] = "dog";
   char* p1 = s1;
   char* p2 = s2;

   // the following is a string copy operation
   while (*p1++ = *p2++);

   // s2 was copied into s1, so now they are both equal to "dog"
   printf_s("%s %s", s1, s2);
}

// pointer_linkedlist.cpp
// compile with: /EHsc
#include <iostream>
using namespace std;

struct NewNode {
   NewNode() : node(0){}
   int i;
   NewNode * node;
};

void WalkList(NewNode * ptr) {
   if (ptr != 0) {
      int i = 1;
      while (ptr->node != 0 ) {
         cout << "node " << i++ << " = " << ptr->i << endl;
         ptr = ptr->node;
      }
      cout << "node " << i++ << " = " << ptr->i << endl;
   }
}

void AddNode(NewNode ** ptr) {
   NewNode * walker = 0;
   NewNode * MyNewNode = new NewNode;
   cout << "enter a number: " << endl;
   cin >> MyNewNode->i;

   if (*ptr == 0)
      *ptr = MyNewNode;
   else  {
      walker = *ptr;
      while (walker->node != 0)
         walker = walker->node;

      walker->node = MyNewNode;
   }
}

int main() {
   char ans = ' ';
   NewNode * ptr = 0;
   do {
      cout << "a (add node)  d (display list)  q (quit)" << endl;
      cin >> ans;
      switch (ans) {
      case 'a':
         AddNode(&ptr);
         break;
      case 'd':
         WalkList(ptr);
         break;
      }
   } while (ans != 'q');
}