C++ programming language

�� C⁺⁺
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�� 14. �� 

�� , �� , � �� 5, �� void �� . �� (�� ) ��, �� . �� , �� , �� , �� .

1. �� . � �� 10 �� , �� . �� , � �� , �� , �� . �� , �� :

// complex1.cpp
// a class that models a complex number data type

#include <iostream.h>

class Complex_number
{
private:
    float real;          // real part
    float imaginary;     // imaginary part
public:
    void set()
    {
      char dummy;        // for comma

      cout << "Enter number (format Re, Im): ";
      cin >> real >> dummy >> imaginary;
    }

    void display()
    {
      cout << '('
           << real       // real part
           << ','
           << imaginary // imaginary part
           << ')';
    }

    float module()
    {
      float m = real*real + imaginary*imaginary;
      return sqrt(m);
    }
}; // class Complex_number

void main()
{
Complex_number c1; // create a complex_number variable
char choice;

do
{
cout << "For c1, ";
c1.set(); // set c1

// calculate module of c1 and assign it to mod
float mod = c1.module();

    cout << "Module of ";
    c1.display();         // display t3
    cout << " = " << mod;

cout << "\nDo another (y/n)? ";
cin >> choice;
} while(choice != 'n');

} //end main

�� module() �� (�� ), �� . �� float �� : float module(). � �� . �� (keyword) return � �� - �� sqrt() � �� . � �� (� main()) �� float mod = c1.module();, �� c1 � �� mod.

2. �� (statement) return. �� , �� , �� (�� - ��  - �� (statement) �� ). �� , �� return � �� . �� return � �� , �� return m;. �� return �� , �� module().

return sqrt(m);

�� return �� . �� , �� , �� return �� . �� , �� module() �� .

1 ��

    float module()
    {
      float m = real*real + imaginary*imaginary;
      cout << "+++++++++++++++++++++++";
      return sqrt(m);
    }

2 ��

    float module()
    {
      float m = real*real + imaginary*imaginary;
      return sqrt(m);
      cout << "+++++++++++++++++++++++";
    }

�� :

1 ��

For c1, Enter number (format Re, Im): 2,3
+++++++++++++++++++++++Module of (2,3) = 3.60555
Do another (y/n)?

2 ��

For c1, Enter number (format Re, Im): 2,3
Module of (2,3) = 3.60555
Do another (y/n)?

� ��, �� , �� return, �� , � �� . ��, �� , �� 11 �� :

// divide the complex number by another one (compl_num)
void div(complex_number compl_num)
{
complex_number cn;

cn.real = real;
cn.imaginary = imaginary;

    float sqr_mod = compl_num.module();
    if (sqr_mod == 0)
    {
      cout << "Devision by zero!" << endl;
      return;
    }

sqr_mod *= sqr_mod;

real = (cn.real*compl_num.real + compl_num.imaginary*cn.imaginary)/sqr_mod;
imaginary = (compl_num.real*cn.imaginary - cn.real*compl_num.imaginary)/sqr_mod;
}

�� , �� sqr_mod (�� , �� ) � ��, �� Devision by zero! � �� div(complex_number compl_num). �� , div(complex_number compl_num), �� - module().

3. �� . �� cn � sqr_mod �� ��  (Automatic Variables). �� . �� cn �� , �� sqr_mod �� , �� module(). �� (Stack).

�� � �� , � �� . �� , � ��, �� . �� . �� , �� , �� . �� , � �� .

�� (Nameless Automatic Variables): �� module() �� :

    float module()
    {
      return sqrt(real*real + imaginary*imaginary);
    }

�� , �� float, �� . �� .

4. �� . �� :

// complex2.cpp
// a class that models a complex number data type

#include <iostream.h>
#include <iomanip.h>

class complex_number
{
private:
    float real;          // real part
    float imaginary;     // imaginery part
public:
    void set()
    {
      char dummy;        // for comma

      cout << "Enter number (format Re, Im): ";
      cin >> real >> dummy >> imaginary;
    }

    void display()
    {
      cout << '('
           << showpoint
           << setprecision(6) << real       // real part
           << ','
           << setprecision(6) << imaginary // imaginary part
           << ')';
    }

    // add to the complex number another one (compl_num)
    void add(complex_number compl_num)
    {
      real += compl_num.real;
      imaginary += compl_num.imaginary;
    }

    // subtract from the complex number another one (compl_num)
    void sub(complex_number compl_num)
    {
      real -= compl_num.real;
      imaginary -= compl_num.imaginary;
    }

   // multiply the complex number by another one (compl_num)
    void mult(complex_number compl_num)
    {
      complex_number cn;
      cn.real = real;
      cn.imaginary = imaginary;

      real = cn.real*compl_num.real - compl_num.imaginary*cn.imaginary;
      imaginary = cn.real*compl_num.imaginary + compl_num.real*cn.imaginary;
    }

    // divide the complex number by another one (compl_num)
    void div(complex_number compl_num)
    {
      complex_number cn;

cn.real = real;
cn.imaginary = imaginary;

      float sqr_mod = compl_num.module();
      if (sqr_mod == 0)
      {
        cout << "Devision by zero!" << endl;
        return;
      }

sqr_mod *= sqr_mod;

      real = (cn.real*compl_num.real + compl_num.imaginary*cn.imaginary)/sqr_mod;
      imaginary = (compl_num.real*cn.imaginary - cn.real*compl_num.imaginary)/sqr_mod;
    }

    // calculate the module of the complex number
    float module()
    {
      float m = real*real + imaginary*imaginary;
      return sqrt(m);
    }

}; // class complex_number

void main()
{
complex_number c1, c2; // create two complex_number variables
char choice;

do
{
    // enter c1
    cout << "For c1, ";
    c1.set();       // set c1

    // enter c1
    cout << "For c2, ";
    c2.set();       // set c2

cout << "\nAdd, Subtract, Multiply or Divide (a/s/m/d)? ";
cin >> choice;

    switch (choice)
    {
      // add c2 to c1 and save the result into c1
      case 'a':
      {
        c1.add(c2);
        c1.display();         // display c1
        break;
      }
      // subtract c2 from c1 and save the result into c1
      case 's':
      {
        c1.sub(c2);
        c1.display();         // display c1
        break;
      }
      // multiply c1 by c2 and save the result into c1
      case 'm':
      {
        c1.mult(c2);
        c1.display();         // display c1
        break;
      }
      // divide c1 by c2 and save the result into c1
      case 'd':
      {
        c1.div(c2);
        c1.display();         // display c1
      }

} // switch choice

cout << "\nDo another (y/n)? ";
cin >> choice;
} while(choice != 'n');

} //end main

�� display() �� showpoint � setprecision. �� , � �� .

� �� c1 � c2 �� complex_number. � �� , �� . � �� switch �� .

5. �� complex_number . �� void � �� :

c1.add(c2);
c1.sub(c2);
c1.mult(c2);
c1.div(c2);

� �� , �� c2 �� c1., �� c2 �� c1 � �.�., �� c1, �.�. c1 �� . �� (�� ), �� , �� :

c3 = c1.add(c2);
c3 = c1.sub(c2);
c3 = c1.mult(c2);
c3 = c1.div(c2);

�� -�� . �� mult(c2) � �� complex_number.

// multiply two complex numbers and assign the result to third one
complex_number mult(complex_number compl_num)
{
complex_number cn;

cn.real = real*compl_num.real - imaginary*compl_num.imaginary;
cn.imaginary = real*compl_num.imaginary + compl_num.real*imaginary;

return (cn);
}

� �� cn � �� , �� . � �� . �� . �� . 4 �� , �� :

c3 = c1.add(c2);
c3 = c1.sub(c2);
c3 = c1.mult(c2);
c3 = c1.div(c2);

�� . 4. �� - complex3.cpp

5. �� . �� , �� . �� airtime - �� timecnv1 �� .

� �� , timecnv2.cpp, �� airtime �� int � �� AirtimeToMins.

int AirtimeToMins()   // convert airtime to minutes
{
     int imins = hours*60 + minutes;
     return imins;
}

imins � �� , �� . �� -�� :

int AirtimeToMins() // convert airtime to minutes
{
return hours*60 + minutes;
}

�� , timeret.cpp, �� (�� airtime) � �� . �� :

airtime add(airtime at2)
{
     airtime temp;
     temp.minutes = minutes + at2.minutes;   // add minutes
     temp.hours = hours + at2.hours;         // add hours

     if(temp.minutes > 59)                   // if carry,
     {
        temp.minutes = temp.minutes - 60;    // adjust minutes
        temp.hours = temp.hours + 1;         // and hours
     }

if(temp.hours > 23) // if carry,
temp.hours = temp.hours - 24; // adjust hours

return temp;
}

�� , � �� add �:

t3 = t1.add(t2); // add t1 and t2, result in t3

� �� �� (arrays) � �� (strings).

^{(��)}

��

[1] Robert Lafore; C++ Interactive Course. Waite Group Press, Macmillan Computer Publishing, 1996.

��: ��. ��

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[ �� 18 �� 2008 �. �� "��" www.kosnos.com ]

Keywords: �++, OOP programming , C++ , Classes , Inheritance , Reusability , Creating New Data Types , Polymorphism and Overloading
�� : �� , ��, �� , �� switch if else ?