// -------------------------------
//  pointer.cpp
// -------------------------------

#include "w.h"

void main()
{
  nl(0);
  banner("pointer.cpp");
  int j = 3;
  int *pj;
  pj = &j;
  p("j = ",j); p("   pj = "); cout << pj;
  pl("  (HEX)");
  double x = Pi;
  p("x = ",x); p("   &x = "); cout << &x << "\n";


  int v[10];
  for (j = 0; j < 5; j++)
	{ v[j] = 20-j;
	  cout << "  v[" << j << "] = ";
	  cout << v[j] << "  ";
	  cout << "  &v[" << j << "] = ";
	  cout << &v[j] << "\n"; } nl();
  p("&v    = "); cout << &v; nl();
  p("&v[0] = "); cout << &v[0] << "\n"; nl();
  int *pv = &v[0];
  pv++; pv++;
  p("int *pv = &v[0],  pv++,  pv++,  pv = ");
	  cout << pv; p("  *pv = ", *pv); nl();
  pv = &v[2]; pv = pv - 1;
  pl("pv = &v[2],  pv = pv - 1,  *pv = ",  *pv);
  

  p("sizeof(int) = ", sizeof(int));
  int vi[100]; vi[0] = 1;
  pl("    int vi[100];   sizeof(vi) = ", sizeof(vi));

  p("sizeof(double) = ", sizeof(double));
  double vx[100]; for (int i = 0; i < 100; i++) vx[i] = Pi;
  pl("   double vx[100];   sizeof(vx) = ", sizeof(vx));
  nl(2);
  double *ux = NULL;
  p("*ux = NULL = "); cout << ux; nl();
  ux = new double[1000]; // memory on the heap
  pl("ux = new double[1000];  sizeof(ux) = ", sizeof(ux));
  p("sizeof(*ux) = ",sizeof(*ux)); pl("  sizeof(ux[0]) = ", sizeof(ux[0]));
  p("ux = "); cout << ux;
  delete [] ux; 
  p("  delete [] ux;  ux = "); cout << ux; nl();
  ux = NULL; // safe
  p("ux = NULL;  ux = "); cout << ux; pl("  safe now");
  nl(2);
  cout.precision(25);
   x = 1.0; x = x/3;
  pl("1.0/3 = ",1.0/3);
  
  cout.precision(8);

  double *a[3]; // array of pointers to double
  x = 2.1; double y = 2.2,z = 2.3;
  p("x = ",x); p("  y = ",y); pl("  z = ",z);
  a[0] = &x;
  a[1] = &y;
  a[2] = &z;
  for (j = 0; j < 3; j++) { p("*a["); p(j); p("] = ", *a[j]); p("  "); } nl();
  double t = *a[0];
  *a[0] = *a[1];
  *a[1] = t;
  p("x = ",x); p("  y = ",y); pl("  z = ",z);

  }
 /*

   -------------
    pointer.cpp
   -------------
   j = 3   pj = 0x243f290a  (HEX)
   x = 3.14159   &x = 0x243f28fc
  v[0] = 20    &v[0] = 0x243f28a6
  v[1] = 19    &v[1] = 0x243f28a8
  v[2] = 18    &v[2] = 0x243f28aa
  v[3] = 17    &v[3] = 0x243f28ac
  v[4] = 16    &v[4] = 0x243f28ae

   &v    = 0x243f28a6
   &v[0] = 0x243f28a6

   int *pv = &v[0],  pv++,  pv++,  pv = 0x243f28aa  *pv = 18
   pv = &v[2],  pv = pv - 1,  *pv = 19
   sizeof(int) = 2    int vi[100];   sizeof(vi) = 200
   sizeof(double) = 8   double vx[100];   sizeof(vx) = 800


   *ux = NULL = 0x00000000
   ux = new double[1000];  sizeof(ux) = 4
   sizeof(*ux) = 8  sizeof(ux[0]) = 8
   ux = 0x2fb700be  delete [] ux;  ux = 0x2fb700be
   ux = NULL;  ux = 0x00000000  safe now


   1.0/3 = 0.333333333333333315
   x = 2.1  y = 2.2  z = 2.3
   *a[0] = 2.1  *a[1] = 2.2  *a[2] = 2.3
   x = 2.2  y = 2.1  z = 2.3


  */