C++/Data Type/pointer

Creating a Stray Pointer

<source lang="cpp"> typedef unsigned short int USHORT;

1. include <iostream>

int main() {

  USHORT * pInt = new USHORT;
  *pInt = 10;
  std::cout << "*pInt: " << *pInt << std::endl;
  delete pInt;
  long * pLong = new long;
  *pLong = 90000;
  std::cout << "*pLong: " << *pLong << std::endl;
  *pInt = 20;      
  std::cout << "*pInt: " << *pInt  << std::endl;
  std::cout << "*pLong: " << *pLong  << std::endl;
  delete pLong;
  return 0;

}

 </source>

Demonstrating Passing by Value

<source lang="cpp">

1. include <iostream>

using namespace std; void swap(int x, int y); int main() {

  int x = 5, y = 10;
  cout << "Main. Before swap, x: " << x << " y: " << y << endl;
  swap(x,y);
  cout << "Main. After swap, x: " << x << " y: " << y << endl;
  return 0;

} void swap (int x, int y) {

  int temp;
  cout << "Swap. Before swap, x: " << x << " y: " << y << endl;
  temp = x;
  x = y;
  y = temp;
  cout << "Swap. After swap, x: " << x << " y: " << y << endl;

}

 </source>

Passing Pointer to a Constant Object

<source lang="cpp">

1. include <iostream>

using namespace std; class SimpleCat {

 public:
   SimpleCat();
   SimpleCat(SimpleCat&);
   ~SimpleCat();
   int GetAge() const { return itsAge; }
   void SetAge(int age) { itsAge = age; }
 private:
   int itsAge;

}; SimpleCat::SimpleCat() {

  cout << "Simple Cat Constructor..." << endl;
  itsAge = 1;

} SimpleCat::SimpleCat(SimpleCat&) {

  cout << "Simple Cat Copy Constructor..." << endl;

} SimpleCat::~SimpleCat() {

  cout << "Simple Cat Destructor..." << endl;

} const SimpleCat * const FunctionTwo

  (const SimpleCat * const theCat);

int main() {

  cout << "Making a cat..." << endl;
  SimpleCat Frisky;
  cout << "Frisky is " ;
  cout << Frisky.GetAge();
  cout << " years old" << endl;
  int age = 5;
  Frisky.SetAge(age);
  cout << "Frisky is " ;
  cout << Frisky.GetAge();
  cout << " years old" << endl;
  cout << "Calling FunctionTwo..." << endl;
  FunctionTwo(&Frisky);
  cout << "Frisky is " ;
  cout << Frisky.GetAge();
  cout << " years old" << endl;
  return 0;

} // functionTwo, passes a const pointer const SimpleCat * const FunctionTwo(const SimpleCat * const theCat) {

  cout << "Frisky is now " << theCat->GetAge();
  cout << " years old " << endl;
  return theCat;

}

 </source>

Returning Values with Pointers

<source lang="cpp">

1. include <iostream>

using namespace std; short Factor(int n, int* pSquared, int* pCubed); int main() {

  int number, squared, cubed;
  short error;
  cout << "Enter a number (0 - 20): ";
  cin >> number;
  error = Factor(number, &squared, &cubed);
  if (!error)
  {
     cout << "number: " << number << endl;
     cout << "square: " << squared << endl;
     cout << "cubed: "  << cubed   << endl;
  }
  else
     cout << "Error encountered!!" << endl;
  return 0;

} short Factor(int n, int *pSquared, int *pCubed) {

  short Value = 0;
  if (n > 20)
     Value = 1;
  else
  {
     *pSquared = n*n;
     *pCubed = n*n*n;
     Value = 0;
  }
  return Value;

}

 </source>