C++ program to implement Constructors and destructors. default, copy, dynamic constructor with memory allocation using new command for 1-d and 2-d arrays.

PROGRAM:

#include<iostream.h>

#include<conio.h>

class code

{

int id;

public:

code()

{ }

code(int a)

{

id = a;

}

code(code &x) // copy constructor

{

id = x.id; // copy in the value

}

void display (void)

{

cout<<id;

}

};

void main()

{

clrscr();

code A(100); // object A is created and initialized

code B(A); // copy constructor called

code C = A; // copy constructor called again

code D; // D is created, not initialized.

D = A; // copy constructor not called

cout <<"\n id of A: ";

A.display();

cout <<"\n id of B: ";

B.display();

cout <<"\n id of C: ";

C.display();

cout <<"\n id of D: ";

D.display();

getch();

}

OUTPUT

id of A: 100

id of B: 100

id of C: 100

id of D: 100

>>>Dynamic constructor with memory allocation using new command for 1-d array

Program Code:

#include<iostream.h>

#include<string.h>

#include<conio.h>

class string

{

char *name;

int length;

public:

string()

{

length = 0;

name=new char[length+1]; //one extra for \0

}

string (char *s)

{

length = strlen(s);

name = new char[length+1];//one extra for \0

strcpy (name,s);

}

void display()

{

cout<<name<<endl;

}

void join (string &a,string &b);

};

void string :: join(string &a, string &b)

{

length = a.length + b.length;

delete name ;

name = new char[length+1]; //dynamic allocation.

strcpy(name,a.name);

strcat(name,b.name);

};

void main ()

{

clrscr();

char *first = "Joseph ";

string name1(first),name2("Louis "),name3("Lagrange"),s1,s2;

s1.join(name1,name2);

s2.join(s1,name3);

name1.display();

name2.display();

name3.display();

s1.display();

s2.display();

getch();

}

OUTPUT

Joseph

Louis

Lagrange

Joseph Louis

Joseph Louis Lagrange

>>>Dynamic constructor with memory allocation using new command for 2-d arrays

Program Code:

#include<iostream.h>

#include<conio.h>

class matrix

{

int **p; //pointer to matrix

int d1,d2; //dimensions

public:

matrix(int x, int y)

{

d1 = x;

d2 = y;

p = new int *[d1]; //creates an array pointer

for(int i = 0; i < d1; i++)

p[i] = new int [d2]; //creates space for each row

}

void get_element(int i, int j, int value)

{

p[i][j] = value;

}

int & put_element(int i, int j)

{

return p[i][j];

}

};

void main ()

{

clrscr();

int m,n;

cout <<"Enter size of matrix : ";

cin >> m >> n;

matrix A(m, n); // matrix object A constructed

cout <<"Enter matrix elements row by row \n";

int i,j,value;

for (i = 0; i < m; i++)

for (j = 0; j< n; j++)

{

cin >> value;

A.get_element(i,j,value);

}

cout <<endl;

cout << A.put_element(1,2);

getch();

}

OUTPUT

Enter size of matrix : 3 4

Enter matrix elements row by row

11 12 13 14

15 16 17 18

19 20 21 22