C++ From Year 1995 File From "V"

 // Filename: VALUPASS.CPP

// Passes an argument from main()

// to another function by value

#include <iostream.h>

void GetIt(int i);   // The function's prototype

void main()

{

  int i;

  

  cout << "I'm now in main()... " << endl;

  cout << "Please enter a value for i: ";

  cin >> i;

  GetIt(i);   // No data types, just the variable

  cout << endl << endl;

  cout << "Back in main(), the value is still "

       << i << endl;

  return;   // Return to the QuickWin

}

//***********************************************************

void GetIt(int i)

{

  // GetIt() now has a local variable called i also

  cout << endl << endl 

       <<"Just got to GetIt() and i is " << i << endl;

  i *= 5;

  cout << "After multiplying by 5, i is now " << i << endl;

  return;   // Return to main()

}

=======================

// Filename: VARS.CPP

 // All programs share common traits

 #include <iostream.h>

 void main()

 {

   char c;             // Define all variables before

   int i;              // you use them

   float f;

   // The next few lines store literal values

   // in the three variables just defined

   c = 'W';

   i = 64;

   f = 12.57;

   // Print the values

   cout << "c is " << c << ", i is " << i << ", f is "

        << f;

 }

=========================

// File name : VIRTUAL.CPP

// Program to demonstrate the difference between

// standard and virtual function calls

//

#include <iostream.h>

class BaseClass

  {

    public:

      void Plain()

        {

          cout << "BaseClass::Plain()" << endl;

        }

      virtual void Virtual()

        {

          cout << "BaseClass::Virtual()" << endl;

        }  

      void CallVirtual()

        {

          Virtual();

        }

   };

class DerivedClass : public BaseClass

  { 

    public:

      void Plain()

        {

          cout << "DerivedClass::Plain()" << endl;

        }

      virtual void Virtual()

        {

          cout << "DerivedClass::Virtual()" << endl;

        }  

  };

  

void main()

  {

    BaseClass baseClass;

    DerivedClass derivedClass;

    

    baseClass.Plain();

    baseClass.Virtual();

    baseClass.CallVirtual();

    cout << endl;

    

    derivedClass.Plain();   

    derivedClass.Virtual();

    derivedClass.CallVirtual();

    cout << endl;

    

    BaseClass * basePointer = &baseClass;

    BaseClass * derivedPointer = &derivedClass;

    // NB type of pointer is base class

    

    basePointer->Plain();

    basePointer->Virtual();

    basePointer->CallVirtual();

    cout << endl;

    

    derivedPointer->Plain();   

    derivedPointer->Virtual();

    derivedPointer->CallVirtual();

    cout << endl;

  }    

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