C and C++ Language

Menu Based C Language Program Using Functions

noreply@blogger.com (Dhananjoy Chakraborty) — Sun, 12 Feb 2012 00:35:00 +0000

This is a C Language program where a number along with choice are entered by user.
According to the choice, the program either print
1. Factors of the number
2. Factorial value of the number
3. Whether the number is prime or not
4. Whether the entered number is perfect or not

#include< stdio.h>
void per(int n)
{
int i,s=0;
for(i=1;i< n;i++)
{
if(n%i==0)
s+=i;
}
if(s==n)
printf("%d is a perfect number.",n);
else
printf( "%d is not a perfect number.",n);
}
void pri(int n)
{
int i;
for(i=2;i< n;i++)
{
if(n%i==0)
break;
}
if(i==n)
printf("%d is a prime number.",n);
else
printf( "%d is not a prime number.",n);}
void fact(int n)
{
int i;
printf("\nFactors of %d are=",n);
for(i=1;i< n;i++)
{
if(n%i==0)
printf(" %d",i);
}
}

void facto(int n)
{
int i,f=1;
for(i=2;i<=n;i++)
{
f=f*i;
}
printf("\nFactorial value =%d",f);
}

void main()
{
int i,n;
printf("Enter the number:");
scanf("%d",&n);
printf("Enter the Choice ('1' for showing factors, '2' for factorial , '3' for prime checking and '4' for perfect number checking:");
scanf("%d",&i);
if(i==1)
fact(n);
else if(i==2)
facto(n);
else if(i==3)
pri(n);
else if(i==4)
per(n);
else
printf("\nWrong Choice..");
getch();
}

C Program on Pattern Printing

noreply@blogger.com (Dhananjoy Chakraborty) — Wed, 18 Jan 2012 01:25:00 +0000

1234554321
1234---4321
123------321
12---------21
1------------1
12---------21
123------321
1234---4321
1234554321

C Programming codes to print the above pattern

#include<stdio.h>
void main()
{
int i,j,x,y=0,k,m,n;
m=5;
for (i=0;i<9;i++)
{
x=1;
for(j=0;j<m;j++)
printf("%d",x++);
for(k=0;k<y;k++)
printf(" ");
x--;
for(j=0;j<m;j++)
printf("%d",x--);
printf("\n");
if(i<9/2)
{
m--;
y=y+3;
}
else
{
m++;
y=y-3;
}
}
getch();
}

Programs on Patterns Using C Language

noreply@blogger.com (Dhananjoy Chakraborty) — Sun, 08 Jan 2012 02:17:00 +0000

Two programs on pattern using C Language are given below

333

55555

7777777

999999999

7777777

55555

333

#include<stdio.h>

void main()

{

int m,n,b=1;

for(m=0; m<5; m++)

{

for(n=0; n<m*2+1; n++)

{

printf("%d",b);

}

b=b+2;

printf("\n");

}

b=b-4;

for(m=0; m<4; m++)

{

for(n=0; n< 7 - m*2; n++)

{

printf("%d",b);

}

b=b-2;

printf("\n");

}

getch();

}

Display the pattern using C Language program.

2_2

3_3_3

4_4_4_4

5_5_5_5_5

4_4_4_4

3_3_3

2_2

#include<stdio.h>

void main()

{

int m,n,b=1;

for(m=0; m< 5; m++)

{

for(n=0; n< m*2+1; n++)

{

if(n%2==0)

printf("%d",b);

else

printf(" ");

}

b=b+1;

printf("\n");

}

b=b-2;

for(m=0; m< 4; m++)

{

for(n=0; n< 7 - m*2; n++)

{

if(n%2==0)

printf("%d",b);

else

printf(" ");

}

b=b-1;

printf("\n");

}

getch();

}

C Language program on pattern

noreply@blogger.com (Dhananjoy Chakraborty) — Sun, 25 Dec 2011 00:32:00 +0000

C Program on printing the following pattern

1AAAA
22BBB
333CC
4444D
55555

#include<stdio.h>

void main()

{

int i,j,k;

for(i=1;i<=5;i++)

{

for(j=1;j<=i;j++)

{

printf("%d",i);

}

for(k=i;k<5;k++)

{

printf("%c",(i+64));

}

printf("\n");

}

getch();

}

Virtual Function and overriding in C++ programs

noreply@blogger.com (Dhananjoy Chakraborty) — Tue, 06 Sep 2011 23:44:00 +0000

Complete study of virtual function, pure virtual function, overriding of virtual function are discussed here.

So far we have seen function overloading and operator overloading. Those are examples of polymorphism. Now we will see another implementation of polymorphism through virtual function. Virtual means existing in effect but not in reality. A virtual function means that does not really exists but appears real to some part of a program.

Suppose we have a number of objects of different classes but we want to put them all in a list and perform a particular operation on them using the same function. Suppose we have three different classes line, circle and triangle. Each class contains a function draw () . The function body statements of the function in different class must be different. Suppose draw () function of line class will draw line, draw () function of circle class will draw a circle and so on. If we want to draw a number of lines, circles and triangles on the screen, we have to create an array of pointers that will contain the addresses of the objects. Using loop and pointer we can access the address of the objects and by calling the draw () function, we will get different output on the screen. When the loop has accessed any object of line class, the draw () function will draw a line. Similar effects will be observed in case of circle or triangle class.

<h2>Program on virtual function</h2>

#include< iostream.h>

#include< conio.h>

class abc

{

public:

void display()

{

cout<< "\nInside base class.";

}

};

class xyz:public abc

{

public:

void display()

{

cout<< "\nInside 1st derived class.";

}

};

class mn:public abc

{

public:

void display()

{

cout<< "\nInside 2nd derived class.";

}

};

void main()

{

clrscr();

xyz ob;

mn ob1;

abc *ptr;

ptr=&ob;

cout<< "\nFor object of 1st derived class."<< endl;

ptr->display();

ptr=&ob1;

cout<< "\nFor object of 2nd derived class."<< endl;

ptr->display();

getch();

}

In the above program we have two derived classes of base or super class abc. All the three classes have a function void display (). Inside the void main () we have created one pointer of the 1st class and two different objects of the derived classes. Next we have assigned the address of the derived class objects on the pointer of the base class. This will not generate any error as address of any derived class can be hold by a pointer of it’s super class. After assigning the address of derived classes we called the display () function. But each time the base class version of display() function will be executed as the pointer type matches with the base class, ignoring the content of the pointer. So this will not provide the required facility as stated earlier (line ,circle and triangle class ).

Now we will make some change in our program. Use the keyword virtual before the function definition.

#include< iostream.h>

#include< conio.h>

class abc

{

protected :

int a,b;

public:

void take()

{

cout<< "\nEnter two values:"<< endl;

cin>>a>>b;

}

virtual void display()

{

cout<< "\nInside base class.";

}

};

class xyz:public abc

{

public:

void display()

{

cout<< "\nSum for 1st derived class="<< a+b;

}

};

class mn:public abc

{

public:

void display()

{

cout<< "\nSum for 2nd derived class:"<< a+b;

}

};

void main()

{

clrscr();

xyz ob;

mn ob1;

abc *ptr;

ptr=&ob;

cout<< "\nFor object of 1st derived class."<< endl;

ptr->take();

ptr->display();

cout<< "\nFor object of 2nd derived class."<< endl;

ptr=&ob1;

ptr->take();

ptr->display();

getch();

}

In the above program the void display () function of the derived classes were executed. If we want to execute the base class version of the display () function, we have create an object of the base class also and assign it’s address on the base class pointer. Next call to the display () function will execute the base class void display () function.

In the above program we have overridden the void display () of the base class in it’s derived classes, but it was not compulsory. We can define a function name void display1 () in class xyz to perform the same work as void display () function. In such case also we can assign the address of xyz class object on the pointer of it’s base class ( here abc *ptr ). Then through the pointer we can call the void take () function for the xyz class object but can not call the void display1 () function through the base class pointer as the base class has no intimation regarding the void display1 () function. But in some cases function overriding may become compulsory. In such situation the base class function ( which must be overridden by it’s derived classes ) should be <b>pure virtual function</b>. A pure virtual function has no body The declaration of a pure virtual function is like :- virtual void display ()=0; In general a virtual function of any super class is never executed. When this is true , the body of the virtual function of a any super class can be removed using the notation =0. When a super class contains any pure virtual function, sub classes which inherits the super class must <b>override the pure virtual function</b>.

A class containing at least a pure virtual function is called abstract class. An abstract class cannot create any object. But pointers can be declared of an abstract class. Other sub classes can inherits an abstract class. Abstract class should be used as base class.

#include< iostream.h>

#include< conio.h>

class abc

{

protected :

int a,b;

public:

void take()

{

cout<< "\nEnter two 'int' values::";

cin>>a>>b;

}

virtual void display()=0;

};

class xyz:public abc

{

public:

void display()

{

cout<< "\nSum for 1st derived class="<< a+b;

}

};

class mn:public abc

{

public:

void display()

{

cout<< "\nSum for 2nd derived class:"<< a+b;

}

};

void main()

{

clrscr();

xyz ob;

mn ob1;

abc *ptr;

ptr=&ob;

cout<< "\nFor object of 1st derived class."<< endl;

ptr->take();

ptr->display();

cout<< "\nFor object of 2nd derived class."<< endl;

ptr=&ob1;

ptr->take();

ptr->display();

getch();

}

Class within Class in C++ Programs

noreply@blogger.com (Dhananjoy Chakraborty) — Tue, 06 Sep 2011 23:40:00 +0000

If two classes are related with one another there can be two types of relationship between them. One type of relationship occurs when a class inherits another class. One type is while one class contains other class’s object as it’s data member. We have seen that while declaring a class there are data members and function members. After declaring a class we can use the object of the class as a data member of another class in the same program.

Here is the C++ program to illustrate the above feature.

#include< iostream.h >

#include< conio.h >

#include< string.h >

class carburettor

{

private:

char name[30];

char type;

float cost;

public:

void setdata(char t,float c,char *m)

{

type=t;

cost=c;

strcpy(name,m);

}

void displaydata()

{

cout<< endl<< type<< endl<< cost<< endl<< name;

}

};

class car

{

private:

char model[30],drivetype[30];

public:

void setdata(char *m,char *d)

{

strcpy(model,m);

strcpy(drivetype,d);

}

void displaydata()

{

cout<< endl<< model<< endl<< drivetype;

}

carburettor c;

};

void main()

{

clrscr();

car mycar;

mycar.c.setdata('A',1000.50,"xyz");

mycar.setdata("sports","4-wheel");

mycar.c.displaydata();

mycar.displaydata();

getch();

}

In the above C++ program the data members of the class carburettor are private, it is completely safe to embed an object of type carburettor as a public member in a new class car. To access the member functions of the carburetor class we have to use the dot operator twice.

It is more common to make the embedded objects private.

#include<iostream.h>

#include<conio.h>

class Name

{

private:

char str[20];//to store the name

char sName[20];//to store the surname

int age;

public:

void take1()

{

cout<< "\nEnter the name (With surname): -";

cin >>str >>sName;

cout<< "\nEnter the age: -";

cin >>age;

}

void display ()

{

cout<< "\nNAME:-\t"<< str<< " "<< sName;

cout<< "\nAGE:-\t"<< age;

}

};

class Details

{

private:

char town[20];

long ph_no;

Name ob;

public:

void take2()

{

ob.take1();

cout<< "\nEnter the town/city name: -";

cin>>town;

cout<< "\nEnter the Phone Number: -";

cin >>ph_no;

}

void display ()

{

ob.display ();

cout<< "\nTOWN:-\t"<< town;

cout<< "\nPHONE NUMBER:_\t"<< ph_no;

}

};

class Last:public Name,public Details

{

private:

char email[40];

public:

void take3()

{

cout<< "\nEnter the E-mail address: -";

cin >>email;

}

void display()

{

Details::display();

cout<< "\nE-MAIL ADDRESS:-\t"<< email;

}

};

void main()

{

Last o[3];

int i;

clrscr ();

for(i=0;i< 3;i++)

{

o[i].take2();

o[i].take3();

}

clrscr ();

for(i=0;i< 3;i++)

{

o[i].display();

}

getch ();

}

Multiple inheritance in C++ Programming Language

noreply@blogger.com (Dhananjoy Chakraborty) — Mon, 05 Sep 2011 23:25:00 +0000

In multiple inheritance in C++ Programs, a derived class inherits a number of classes which are not linked with one another.

Here is an Inheritance in C++ with example

#include< iostream.h >

#include< stdio.h >

#include< conio.h >

class str

{

private:

char name [40],address [40];

public:

void getData1 ()

{

fflush(stdin);

puts("Enter the name: -");

gets(name);

fflush (stdin);

puts("Enter the address: -");

gets(address);

}

void display1 ()

{

cout<< name<< endl;

cout<< "Address: -"<< address<< endl;

}

};

class num

{

private:

int age;

long tel_no;

public:

void getData2 ()

{

cout<< "Enter the age: -";

cin >>age;

cout<< "Enter the Telephone Number: -";

cin >>tel_no;

}

void display2 ()

{

cout<< "Age: -"<< age<< endl;

cout<< "Telephone Number: -"<< tel_no<< endl;

}

};

class final:public str,public num

{

private:

char gender [10];

public:

void getData3 ()

{

cout<< "Enter the gender(Mr./Miss.): -";

cin >>gender;

}

void display3 ()

{

cout<< gender<< " ";

}

};

void main ()

{

clrscr ();

final ob1,ob2;

cout<< "For the 1st object:-"<< endl;

ob1.getData1 ();

ob1.getData2 ();

ob1.getData3 ();

cout<< "For the 2nd object:-"<< endl;

ob2.getData1 ();

ob2.getData2 ();

ob2.getData3 ();

clrscr ();

cout<< "1st object values are: -"<< endl;

ob1.display3 ();

ob1.display1 ();

ob1.display2 ();

cout<< endl<< "Press any key to continue.........";

getch ();

clrscr ();

cout<< endl<< "2nd object values are: -"<< endl;

ob2.display3 ();

ob2.display1 ();

ob2.display2 ();

getch ();

}

In the above C++ program on inheritance, the class 'str' contains two private data members - char name [40],address [40]; and two public function members void getData1 () and void display1 ().

There is another class in the above program 'num'. This class also contains two private data members int age;long tel_no; and two public function members - void getData2 () and void display2 ().

The third class is 'final' which inherits both the above classes. This is an example of multiple inheritance where a derived class can have a number of different classes.

As the data members are declared private in str and num, they can not be accessed in class final. So these members are accessed through the functions of the class itself. To access the data members from the derived class the following modification is needed.

After modification Inheritance in C++ with example

#include< iostream.h >

#include< stdio.h >

#include< conio.h >

class str

{

protected:

char name [40],address [40];

public:

};

class num

{

protected:

int age;

long tel_no;

};

class final:public str,public num

{

private:

char gender [10];

public:

void getData ()

{

fflush(stdin);

cout<< "Enter the gender(Mr./Miss.): -";

cin >>gender;

puts("Enter the name: -");

gets(name);

fflush (stdin);

puts("Enter the address: -");

gets(address);

cout<< "Enter the age: -";

cin >>age;

cout<< "Enter the Telephone Number: -";

cin >>tel_no;

}

void display ()

{

cout<< gender<< " ";

cout<< name<< endl;

cout<< "Address: -"<< address<< endl;

cout<< "Age: -"<< age<< endl;

cout<< "Telephone Number: -"<< tel_no<< endl;

}

};

void main ()

{

clrscr ();

final ob1,ob2;

cout<< "For the 1st object:-"<< endl;

ob1.getData ();

cout<< "For the 2nd object:-"<< endl;

ob2.getData ();

clrscr ();

cout<< "1st object values are: -"<< endl;

ob1.display ();

cout<< endl<< "Press any key to continue.........";

getch ();

clrscr ();

cout<< endl<< "2nd object values are: -"<< endl;

ob2.display ();

getch ();

}

Again modifications are done on the above C++ program. The data members are declared private in the base classes and all the three classes have their own void getData () and void display () functions. The derived class final inherits the two classes by using the statement class final:private str,private num . So the members of str and num are not accessible outside the respective class. So, to enter values we will call the getData () function of the derived class final and from within the function the functions of the base classes will be called.

#include< iostream.h >

#include< stdio.h >

#include< conio.h >

class str

{

private:

char name [40],address [40];

public:

void getData ()

{

fflush(stdin);

puts("Enter the name: -");

gets(name);

fflush (stdin);

puts("Enter the address: -");

gets(address);

}

void display ()

{

cout<< name<< endl;

cout<< "Address: -"<< address<< endl;

}

};

class num

{

private:

int age;

long tel_no;

public:

void getData ()

{

cout<< "Enter the age: -";

cin >>age;

cout<< "Enter the Telephone Number: -";

cin >>tel_no;

}

void display ()

{

cout<< "Age: -"<< age<< endl;

cout<< "Telephone Number: -"<< tel_no<< endl;

}

};

class final:private str,private num

{

private:

char gender [10];

public:

void getData ()

{

cout<< "Enter the gender(Mr./Miss.): -";

cin >>gender;

str::getData ();

num::getData ();

}

void display ()

{

cout<< gender<< " ";

str::display ();

num::display ();

}

};

void main ()

{

clrscr ();

final ob1,ob2;

cout<< "For the 1st object:-"<< endl;

ob1.getData ();

cout<< "For the 2nd object:-"<< endl;

ob2.getData ();

clrscr ();

cout<< "1st object values are: -"<< endl;

ob1.display ();

cout<< endl<< "Press any key to continue.........";

getch ();

clrscr ();

cout<< endl<< "2nd object values are: -"<< endl;

ob2.display ();

getch ();

}

#include< iostream.h >

#include< conio.h >

class A

{

public:

void show()

{

cout<< "\nInside class A.";

}

};

class B

{

public:

void show()

{

cout<< "\nInside class B.";

}

};

class C:public A,public B

{

};

void main()

{

C ob;

ob.show()//error generated in this statement

ob.A::show();

ob.B::show();

getch();

}

In the above C++ program both the classes A and B have show () function. Object of derived class C can access both but not directly.

When we inherit a base class privately , the derived class has all the data and functions of the base class, but the functionality is hidden, means the members of the base class can be accessed in the derived class but not outside it. When we inherits privately all the public and protected members of the base class becomes private members of the derived class. To demonstrate this feature the same program is modified again.

Another program on Inheritance in C++ with example

#include< iostream.h >

#include< stdio.h >

#include< conio.h >

class str

{

private:

char name [40],address [40];

public:

void getData ()

{

fflush(stdin);

puts("Enter the name: -");

gets(name);

fflush (stdin);

puts("Enter the address: -");

gets(address);

}

void display ()

{

cout<< name<< endl;

cout<< "Address: -"<< address<< endl;

}

};

class num

{

protected:

/* modification is done here. Data members are declared as protected*/

int age;

long tel_no;

public:

void getData ()

{

cout<< "Enter the Telephone Number: -";

cin >>tel_no;

}

void display ()

{

cout<< "Age: -"<< age<< endl;

cout<< "Telephone Number: -"<< tel_no<< endl;

}

};

class final:private str,private num

{

private:

char gender [10];

public:

void getData ()

{

cout<< "Enter the gender(Mr./Miss.): -";

cin >>gender;

cout<< "Enter the age: -";

cin >>num::age;

/* now the protected member of the base class num is accessed hare. As num is derived privately , the derived class can not access it’s protected member directly*/

str::getData ();

num::getData ();

}

void display ()

{

cout<< gender<< " ";

str::display ();

num::display ();

}

};

void main ()

{

clrscr ();

final ob1,ob2;

cout<< "For the 1st object:-"<< endl;

ob1.getData ();

cout<< "For the 2nd object:-"<< endl;

ob2.getData ();

clrscr ();

cout<< "1st object values are: -"<< endl;

ob1.display ();

cout<< endl<< "Press any key to continue.........";

getch ();

clrscr ();

cout<< endl<< "2nd object values are: -"<< endl;

ob2.display ();

getch ();

}

Constant function member in C++ programming

noreply@blogger.com (Dhananjoy Chakraborty) — Mon, 05 Sep 2011 23:21:00 +0000

A constant function member can never modify any of its class’s data member.

const keyword to used to define constant function.

#include< iostream.h >

#include< conio.h >

class sample

{

private:

int count;

public:

sample()

{

count=0;

}

void change()

{

count=10;

}

void show()const

{

count=12;/* this statement will show error in compile time */

cout<< "\nThe data member:"<< count;

}

};

void main()

{

clrscr();

sample sp1;

sp1.change();

sp1.show();

getch();

}

Access specifiers in C++ programming

noreply@blogger.com (Dhananjoy Chakraborty) — Mon, 05 Sep 2011 23:20:00 +0000

Here are the different access specifiers in C++ programming language.

pubic members

public members of any class can be accessed from outside the class. For this reason function members are generally public as they should be accessed from outside the class. To make a member public, explicitly declare the member as public ( keyword). Normally we declare data members as private ( not in case of inheritance) and method members as public.

private members

private members can be accessed only from within a class where they are declared. A private member can neither be accessed by member function outside the class nor it can be inherited to a new class.

protected members

Protected members can not be accessed by member functions outside the class, but it allows to inherit the members to a new class

static members in C++

A data member of a class can be made static data member.

#include< iostream.h>

#include< conio.h>

#include< iomanip.h>

class student

{

static int roll;

private:

char name[30];

int m1,m2,m3,total;

float per;

public:

void accept();

void calculate();

void display();

};

int student::roll=1;

void student::accept()

{

cout<< "\nEnter the student record:";

roll++;

cout<< "\nEnter the name:";

cin >>name;

cout<< "\nEnter three marks:";

cin >>m1 >>m2 >>m3;

}

void student::calculate()

{

total=m1+m2+m3;

per=total/3.0;

}

void student::display()

{

cout<< "\nRecord of the student is:";

cout<< setw(4)<< roll<< setw(15)<< name<< setw(4)

<< m1<< setw(4)<< m2<< setw(4)<< m3<< setw(4)<< total<< setw(10.2)<< per;

}

void main()

{

clrscr();

student st1,st2;

cout<< "\nFor 1st object:";

st1.accept();

st1.calculate();

st1.display();

cout<< "\nFor 2nd object:";

st1.accept();

st1.calculate();

st1.display();

getch();

}

In case of static data member only one copy of the member is created for the entire class and is shared by all the objects of that class. A static data member is useful when all objects of a class must share a common item of information. A static data member is available only within the class. A static data member requires an unusual format. For normal variables they can be declared and defined in the same statement (compiler sets aside memory to hold the variable). Static data members requires two different statements. The variable declaration appears in the class while defined outside the class. This special approach for static data members is due to the reason that if they were defined inside a class, it would violate the idea that class declaration is only a blueprint and does not aside any memory.

The declaration and definition of a static member is a must. If we simply declare a static member and forget to define it, compiler will show error. On the other hand while defining a static member, the class name is a must, otherwise linker will show error.

Like static data members there can be static function members also in C++ language.

#include< iostream.h>

#include< conio.h>

class sample

{

private:

static int count;

public:

sample()

{

count++;

}

static void show()

{

cout<< endl<< "COUNT="<< count;

}

};

int sample::count=0;

void main()

{

clrscr();

sample sp1;

sample::show();

sample sp2;

sample::show();

getch();

}

In general static functions accessed in class reference although they can be accessed using object of the class. Ordinary functions can not be accessed using class name.

Inheritance in C++ with example

noreply@blogger.com (Dhananjoy Chakraborty) — Mon, 05 Sep 2011 01:30:00 +0000

Inheritance is the process by which the object of a derived or sub class can acquire the properties of an existing class. Suppose we want to change the above program so that it’s object will contain another long type variable to store the phone number. It is not always possible to modify the class. So we inherits the properties of the object of the above class (here person) to another class Phone and add new features in the class Phone. Ultimately we will create objects of class Phone.

Here is the sample C++ program on Inheritance.

#include< iostream.h>

#include< stdio.h>

#include< conio.h>

class person

{

protected:

char name [40];

public:

void setName ()

{

puts ("Enter Name: -");

gets (name);

}

};

class Phone: public person /* class Phone is a derived class of person*/

{

private:

long phone_no;

public:

void getPhone ()

{

cout<< "Enter the Phone Number: -";

cin >>phone_no;

}

void display ()

{

cout<< "\nName is: -"<< name;

cout<< "\t"<< phone_no;

}

};

void main ()

{

clrscr ();

Phone p;

Phone *ptr [10];

int n=0;

char choice;

{

ptr [n]=new Phone;

ptr [n]->setName ();

ptr [n]->getPhone ();

n++;

fflush (stdin);

cout<< "Another (y/n): -";

cin >>choice;

} while (choice=='y');

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

{

ptr [i]->display ();

}

getch ();

}

new and delete operators in C++ programs

noreply@blogger.com (Dhananjoy Chakraborty) — Mon, 05 Sep 2011 01:29:00 +0000

In C language we used malloc () and calloc () function for dynamic memory allocation. The memory allocated through malloc () or calloc () functions can be vacated using free () function. C++ language provides a better way to accomplish the same job through the use of new and delete operators. The new operator allocates memory from the free store while delete operator returns the memory to the free store.

#include< iostream.h >

#include < conio.h >

#include< string.h >

void main ()

{

clrscr ();

int len;

char *str1;

char *str="Satavisha.";

len= strlen (str);

str1=new char [len+1];

strcpy (str1, str);

cout<< str1;

getch ();

}

Another C++ program of same type.

#include< iostream.h >

#include< conio.h >

#include< stdio.h >

class person

{

private:

char name [40];

public:

void setName ()

{

puts ("Enter Name: -");

gets (name);

}

void display ()

{

cout<< "\nName is: -"< <name;

}

};

void main ()

{

clrscr ();

person *ptr [10];

int n=0;

char choice;

{

ptr [n]=new person;

ptr [n]->setName ();

n++;

fflush (stdin);

cout<< "Another (y/n): -";

cin >>choice;

} while (choice=='y');

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

{

ptr [i]->display ();

}

getch ();

}

Member Functions defined outside the class in C++ program

noreply@blogger.com (Dhananjoy Chakraborty) — Mon, 05 Sep 2011 01:28:00 +0000

In our previous examples we have defined all functions within the class body. C++ program allows defining functions outside the body of classes also. In such case we have to declare the functions within the class body.

Here is a C++ program to demonstrate the above feature.

#include< iostream.h>

#include< conio.h>

class Rect

{

private:

int len, br;

public:

void getData ();

void setData (int l, int b);

void displayData ();

void area ();

Rect (int a, int b);

Rect ();

};

void Rect::getData ()

{

cout<< endl<< "Enter Length and Breadth: -";

cin >>len >>br;

}

void Rect::setData (int l, int b)

{

len=l;

br=b;

}

void Rect::displayData ()

{

cout<< endl<< "Length="<< len;

cout<< endl<< "Breadth="<< br;

}

void Rect::area ()

{

int a, p;

a=len*br;

p=2*(len+br);

cout<< endl<< "Area="<< a;

cout<< endl<< "Perimeter="<< p;

}

Rect::Rect ()

{

}

Rect::Rect (int a, int b)

{

len=a;

br=b;

}

void main ()

{

clrscr ();

Rect r1 (2,3), r2, r3;

cout<< endl<< "For object number 1: -";

r1.displayData ();

r1.area ();

cout<< endl<< "For object number 2: -";

r2.setData (3,5);

r2.displayData ();

r2.area ();

cout<< endl<< "For object number 3: -";

r3.getData ();

r3.displayData ();

r3.area ();

getch ();

}

this pointer in C++ Programs

noreply@blogger.com (Dhananjoy Chakraborty) — Mon, 05 Sep 2011 01:26:00 +0000

Normally pointers can hold the address of it’s own type of variable. this is a keyword used to denote a pointer which can hold the address of any type of location. In C++ programs, this pointers are used to hold the address of objects of any class.

#include< iostream.h >

#include< conio.h >

class Exam

{

private:

int i;

public:

void setData (int a)

{

this->i=a;

cout<< "Address of the object is: -"<< this;

}

void show ()

{

cout<< "\nData member="<< this->i;

}

};

void main ()

{

clrscr ();

Exam s1, s2;

int i;

cout<< "\nEnter value for 1st object: -";

cin>>i;

s1.setData (i);

s1.show ();

cout<< "\nEnter value for 2nd object: -";

cin>>i;

s2.setData (i);

s2.show ();

getch ();

}

String compare using operator overloading

noreply@blogger.com (Dhananjoy Chakraborty) — Sat, 03 Sep 2011 23:52:00 +0000

In C Language, we use strcmp() or strcmpi() functions to compare two strings. In C++ programs also we use these functions to perform the same job. Operator overloading in C++ helps us to use equality operator to compare two strings in C++ programs.

Here is a C++ program to compare two strings using operator overloading.

#include< iostream.h >

#include< conio.h >

#include< string.h >

const int SIZE=40;

class String

{

private:

char str [SIZE];

public:

String ()

{

strcpy (str," ");

}

String (char ch [])

{

strcpy (str, ch);

}

void getString ()

{

cout<< "Enter the string: -";

cin.get (str, SIZE);

}

int operator == (String s)

{

if (strcmp (str, s.str)==0)

return 1;

else

return 0;

}

};

void main ()

{

clrscr ();

String s1, s2, s3;

s1="Satavisha";

s2="Suddhashil";

s3.getString ();

if (s3==s1)

cout<< "1st and 3rd string are same.";

else if (s2==s3)

cout<< "2nd and 3rd string are same.";

else

cout<< "All strings are unique.";

getch ();

}

Operator overloading is an important chapter in and Students can ask any related question through this blog.

Overloading binary and unary operators in C++ programs

noreply@blogger.com (Dhananjoy Chakraborty) — Sat, 03 Sep 2011 23:48:00 +0000

We are working on overloading of operators in C++ programs. In the following program both unary and binary operators are overloaded . I think this C++ program would help students.

#include< iostream.h >

#include< conio.h >

#include< stdio.h >

#include< string.h >

class Count

{

private:

char str[40];

char address[40];

int age;

public:

Count()

{

strcpy(str,"***");

strcpy(address,"!!!!");

age=0;

}

void operator ++ ()

{

cout<< "\nEnter Your name:-";

gets(str);

}

void operator--()

{

cout<< "\nEnter your address( Town/City):-";

cin>>address;

}

void operator +()

{

cout<< "\nEnter your age:-";

cin>>age;

}

void operator -()

{

cout<< "\nName="<< str;

cout<< "\nAddress="<< address;

cout<< "\nAge="<< age;

}

};

void main ()

{

clrscr ();

Count c1;

char ch;

cout<< "\nWant to enter name (y/n):-";

cin>>ch;

if(ch=='y')

++c1;

cout<<"\nWant to enter address (y/n):-";

cin>>ch;

if(ch=='y')

--c1;

cout<< "\nWant to enter age (y/n):-";

cin>>ch;

if(ch=='y')

+c1;

-c1;

getch ();

}

Overloading binary operators in C++ programs

noreply@blogger.com (Dhananjoy Chakraborty) — Sat, 03 Sep 2011 23:46:00 +0000

Operator overloading is a very useful chapter in C++. Here is a C++ program demonstrating the technique of overloading binary operator. Hope this will be helpful to students.

#include< iostream.h >

#include< conio.h >

#include< string.h >

class Count

{

private:

char str1 [10], str2 [10];

public:

void get ()

{

cout<< "Enter the 1st string: -";

cin>>str1;

cout<< "Enter the 2nd string: -";

cin>>str2;

}

char *operator + ()

{

strcat (str1, str2);

return str1;

}

};

void main ()

{

clrscr ();

Count c1;

char str3 [20];

c1.get ();

strcpy (str3, +c1);

cout<< "\nAfter Concatenate ="<< str3;

getch ();

}

We have used different string manipulating functions in C++ programs. Suppose we wand to append one string at the end of other string, we normally invoke library function strcat(). The same operation can done using the + operator through operator overloading in C++ programs. Similar related operations can also be done.

#include< iostream.h >

#include< conio.h >

#include< string.h >

class String

{

private:

char str [100];

public:

String ()

{

strcpy (str," ");

}

String (char ch [])

{

strcpy (str, ch);

}

void display ()

{

cout<< endl<< str;

}

String operator + (String s)

{

String t;

strcpy (t.str, str);

strcat (t.str, s.str);

return t;

}

};

void main ()

{

clrscr ();

String s1, s2,s3;

s1="Satavisha ";

s2="Suddhashil";

s1.display ();

s2.display ();

s3=s1+s2;

s3.display ();

getch ();

}

Any doubt or question can be asked through comments.

Operator Overloading in C++ programs

noreply@blogger.com (Dhananjoy Chakraborty) — Sat, 03 Sep 2011 23:42:00 +0000

Operator overloading is one of the most exciting feature of object-oriented programming. Operator overloading provides normal C++ operators, such as +, -, * etc additional meanings when they are applied to user defined data types. Normally we know that operators like + works only with basic types like int, float etc. Using overloading we can apply these operators on objects also.

Here is one of the C++ programs to demonstrate operator overloading.

#include< iostream.h>

#include< conio.h>

class Count

{

private:

int count;

public:

Count ()

{

count=0;

}

int getCount ()

{

return count;

}

void operator ++ ()

{

count++;

}

};

void main ()

{

clrscr ();

Count c1, c2;

cout<< "\nc1="<< c1.getCount ();

cout<< "\nc2="<< c2.getCount ();

++c1;

++c2;

cout<< "\nc1="<< c1.getCount ();

cout<< "\nc2="<< c2.getCount ();

getch ();

}

The unary operator ++ acts on objects c1 and c2 because the keyword operator is used and which is a must to overload the ++ operator in the function operator ++ (). This syntax tells the compiler to call the member function whenever the operator ++ is encountered, provided the operand is of type Count, the class here. If the operator ++ is used on variables of predefined type like int or float then the compiler will use its built-in routine to increment the value of the variable of int or float type.

Operator Overloading in C++ programs Part I

noreply@blogger.com (Dhananjoy Chakraborty) — Sat, 03 Sep 2011 00:09:00 +0000

Operator overloading is one of the most exciting feature of object-oriented programming and this is included in cbse syllabus. Operator overloading provides normal C++ operators, such as +, -, * etc additional meanings when they are applied to user defined data types. Normally we know that operators like + works only with basic types like int, float etc. Using overloading we can apply these operators on objects also.

Here is one program to demonstrate operator overloading.

#include< iostream.h>

#include< conio.h>

class Count

{

private:

int count;

public:

Count ()

{

count=0;

}

int getCount ()

{

return count;

}

void operator ++ ()

{

count++;

}

};

void main ()

{

clrscr ();

Count c1, c2;

cout<< "\nc1="<< c1.getCount ();

cout<< "\nc2="<< c2.getCount ();

++c1;

++c2;

cout<< "\nc1="<< c1.getCount ();

cout<< "\nc2="<< c2.getCount ();

getch ();

}

The unary operator ++ acts on objects c1 and c2 because the keyword operator is used and which is a must to overload the ++ operator in the function operator ++ (). This syntax tells the compiler to call the member function whenever the operator ++ is encountered, provided the operand is of type Count, the class here. If the operator ++ is used on variables of predefined type like int or float then the compiler will use its built-in routine to increment the value of the variable of int or float type.

Destructors in C++ programs

noreply@blogger.com (Dhananjoy Chakraborty) — Sat, 03 Sep 2011 00:06:00 +0000

When an object is destroyed in C++ programs, a function called destructor automatically gets called. A destructor has the same name as the constructor but it proceeded by a tilde. During the creation of an object constructor is called and destructor function is invoked when the control leaves the main () function. The most common use of destructor is to de-allocate memory that was allocated for the object by constructor.

#include< iostream.h >

#include< conio.h >

class Rect

{

private:

int x;

public:

Rect ()

{

cout<< "Inside constructor.";

}

~Rect ()

{

cout<< "Inside destructor.";

}

};

void main ()

{

Rect r1;

getch ();

}

Constructor in C++ programs

noreply@blogger.com (Dhananjoy Chakraborty) — Sat, 03 Sep 2011 00:04:00 +0000

Constructors are a special type of function whose body must be executed at the time of creating any object. Constructors are special because they have the same name as the class with no return type. A constructor body defines what occurs when an object of a class is created. However, if no explicit constructor is defined, compiler will supply a zero argument empty body constructor. So, to initialize the data members of an object we can use constructor.

#include< iostream.h >

#include< conio.h >

class Rect

{

private:

int len, br;

public:

void getData ()

{

cout<< endl<< "Enter Length and Breadth: -";

cin>>len>>br;

}

void setData (int l, int b)

{

len=l;

br=b;

}

void displayData ()

{

cout<< endl<< "Length="<< len;

cout<< endl<< "Breadth="<< br;

}

void area ()

{

int a, p;

a=len*br;

p=2*(len+br);

cout<< endl<< "Area="<< a;

cout<< endl<< "Perimeter="<< p;

}

Rect ()

{

}

Rect (int a, int b)

{

len=a;

br=b;

}

};

void main ()

{

clrscr ();

Rect r1 (2,3), r2, r3;

cout<< endl<< "For object number 1: -";

r1.displayData ();

r1.area ();

cout<< endl<< "For object number 2: -";

r2.setData (3,5);

r2.displayData ();

r2.area ();

cout<< endl<< "For object number 3: -";

r3.getData ();

r3.displayData ();

r3.area ();

getch ();

}

Here note that the constructor is defined twice in the class Rect. In this program this is a must, as the object r1 will be created after execution of the argument constructor and r2, r3 are created with the help of zero argument empty body constructor. In a class we can have two or more functions with the same name, as long as their parameter declarations are different. When this is the case the functions are said to be overloaded. Function overloading is an example of polymorphism.

Encapsulation in C++ programs

noreply@blogger.com (Dhananjoy Chakraborty) — Sat, 03 Sep 2011 00:01:00 +0000

In my last post, encapsulation is discussed. Encapsulation is very much important for cbse students. In most of the cbse C++ sample paper, you will find at least 2-3 programs purely based on encapsulation. Here is a program demonstrating encapsulation in C++.

#include< iostream.h >

#include< conio.h >

class Rect

{

private:

int len, br;

public:

void getData ()

{

cout<< endl<< "Enter Length and Breadth: -";

cin>>len>>br;

}

void setData (int l, int b)

{

len=l;

br=b;

}

void displayData ()

{

cout<< endl<< "Length="<< len;

cout<< endl<< "Breadth="<< br;

}

void area ()

{

int a, p;

a=len*br;

p=2*(len+br);

cout<< endl<< "Area="<< a;

cout<< endl<< "Perimeter="<< p;

}

};

void main ()

{

clrscr ();

Rect r1, r2, r3;

cout<< endl<< "For object number 1: -";

r1.setData (10,20);

r1.displayData ();

r1.area ();

cout<< endl<< "For object number 2: -";

r2.setData (3,5);

r2.displayData ();

r2.area ();

cout<< endl<< "For object number 3: -";

r3.getData ();

r3.displayData ();

r3.area ();

getch ();

}

The class Rect specified in the above C++ program contains two data members’ len and br and four function members getData (), setData (), displayData () and area (). The first function getData (int, int) takes two integer values from the user and set them in the two data members of the object of Rect class. setData () function sets constant values in the data items of the object. displayData () function displays the values of the data members of an object of class Rect while area () function calculates and displays the area and perimeter.

The body of the class Rect contains two unfamiliar keywords private and public. They are used in C++ programs to implement a concept known as data hiding, encapsulation in C++. private data and function members can be accessed from within the class where public members are accessible from outside the class. The function members provide controlled access to the data members of an object. Usually the data members within a class are private and the function members are public. When the class is created let’s have a look how main () function makes use of it.

Rect r1, r2, r3; defines three objects r1, r2 and r3 of class Rect. Remember that the specifications of the class does not create any object, it only describes how the objects will look when they are created. It is the definition that actually creates objects, which can be used by the program. Thus, defining an object is similar to defining a variable of any data type- space is set-aside for it in memory.

Next is r1.setData (10, 20); this statement does not look like a normal function call. The name of the object r1 is associated to the function using a dot (.). This syntax is used to call a function member that is associated with a specific object.

Basic concepts of Object Oriented Programming

noreply@blogger.com (Dhananjoy Chakraborty) — Thu, 01 Sep 2011 00:02:00 +0000

In Object Oriented Programming the problem is divided into objects and then build data and functions around these objects. The combination of data and functions make up an object.

The data of an object can be accessed only by the functions associated with the object.

What is class

Most languages offer primitive data types like: - int, long, float etc. Their data representations and response to different operators are defined as a part of the language. The language does not know user defined data types. The programmer defines its format and behavior by defining a class. So, a class is a user defined new data type, which serves as a template, and an object is an instance of a class. It specifies what data and functions will be included in objects of the class. A class may be thought of a data type and an object as a variable of that data type. Once a class has been defined we can create any number of objects of that class.

Main features of object oriented programming

1. Encapsulation: - The wrapping up of data and function into a single unit (called class) is called encapsulation. The data is not accessible to the outside world and only those functions, which are wrapped in the class, can access it.

2. Inheritance: - This is a mechanism by which one object acquires the properties of another object of different class. Inheritance is probably the most powerful feature of object-oriented programming. Inheritance is the process of creating new classes, called derived or sub classes from existing classes. The existing classes are called base or super classes. In OOP, the concept of inheritance provides the idea of reusability. This means that we can add additional features to an existing class without modifying it. This is possible by deriving a new class from the existing one.

3. Polymorphism: - This is another OPP concept. It means ‘many forms’ i.e. the ability to take more than one form. For example, an operation can exhibit different behavior in different situation.

const references in C++ programs

noreply@blogger.com (Dhananjoy Chakraborty) — Wed, 31 Aug 2011 23:59:00 +0000

We have seen that we can pass reference of a variable to a function in C++ programs if we want to change the variable value within the function. This can be achieved by using pointer also. But if we don’t want to change the value of the variable ? In such case we can pass the value ( call by value) to the function. But this style has some drawback. If we pass the variable by value then it would be collected in another variable – so creation of another variable. We can avoid such creation of variables by passing the variable by reference. Still there is some trouble. The variables may get modified within the function. This can be prevented by declaring them constant.

C++ program for cbse students to demonstrate use of const in reference variable

#include< iostream.h >

#include< conio.h >

void add(int const &i,int const &j)

{

int m=i+j;

cout<<endl<< "Address of 'm':"<<&m;

cout<<endl<< "Sum="<< m;

//i=10;/* such statement will show compile time error */

}

void main()

{

clrscr();

int a,b;

cout<< "Enter values for 'a' and 'b':";

cin>>a>>b;

cout<< endl<< "Address of 'a' and 'b':"<< &a<< ","<< &b;

cout<< endl<< "Values before calling the function:"<< a<<","<< b;

add(a,b);

cout<< endl<< "Values after calling the function:"<< a<< ","<< b;

getch();

}

The const qualifier in C++ programs

noreply@blogger.com (Dhananjoy Chakraborty) — Wed, 31 Aug 2011 23:57:00 +0000

Todays topic in our C++ tutorial is const qualifier.

If a const keyword precedes the data type of a variable, it means that the variable will not change it’s value throughout the program. Variables with this qualifier are often named in all uppercase, as a reminder that they are constants. const keyword replaces #define statement in C. const is a better idea as compared to #define because it’s scope of operation can be controlled by placing it appropriately either inside a function or outside all functions. If a const variable is declared inside a function that means it becomes local variable to that function which is not possible with #define statement. Like const variables, there can be const pointers also. const pointer will point a fixed value and it can not changed although the pointer can hold the address of other variable.

C++ program to demonstrate use of const in pointer

#include< iostream.h >

#include< conio.h >

void main()

{

clrscr();

int a,b;

const int *ptr;

ptr=&a;

cout<< "Enter values for 'a' and 'b':";

cin>>a>>b;

cout<<endl<<"Value of 'a' through pointer:"<< *ptr;

// ptr=19; / wrong it can not change value */

ptr=&b;

cout<< endl<< "Value of 'b' through pointer:"<< *ptr;

getch();

}

Reference variable and pointer in C++ programs

noreply@blogger.com (Dhananjoy Chakraborty) — Tue, 30 Aug 2011 23:57:00 +0000

Todays topic in our C++ tutorial is Comparision between Reference variable and pointer in C++ programs.

Now we will see the advantage of referencing in C++ programs. Both pointer and reference variable have the same effect while they deals with a variable. But reference variable works in more elegant style. Referencing provides a clean, elegant and efficient way to pass arguments to functions that intend to change their values.

In this C++ program, we will create two structure type variables to store three types of values ( name, age and salary ) in each of them. Then we will change the values using two functions – for one variable 1st function will take address of the variable and other function will take reference of the second variable.

#include< iostream.h >

#include< conio.h >

#include< string.h >

struct tag

{

char name[30];

int age;

};

typedef struct tag EMP;

void fun1(EMP *emp1)

{

strcpy(emp1->name,"Shatavisha");

emp1->age=7;

}

void fun2(EMP &emp2)

{

strcpy(emp2.name,"Sarbani");

emp2.age=36;

}

void main()

{

clrscr();

EMP emp1={"Dhananjoy",42};

EMP emp2={"Sudhyashil",1};

fun1(&emp1);

cout<< endl<< emp1.name<< ","<< emp1.age;

fun2(emp2);

cout<< endl<< emp2.name<<","<< emp2.age;

getch();

}