In a
C++ programming we can create static function and variable by using the
“static” keyword.
Static Variables
In C++ programming we
can create a static variable by placing the “static” keyword before the
variable declaration.
Once a variables declared as static, only one copy of that variable is created for the whole
class.
When a variable is declared as static, by default it is initialize to zero.
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#include <iostream>
using namespacestd;
classExample{
staticintx;
inty;
public:
voidshow(){
y=0;
}
voidcount(){
++x;
++y;
cout<<"\n value of x="<<x;
cout<<"\n value of y="<<y;
}
};
intExample::x=0;//initialization of static member variable
intmain(){
Examplea,b,c;
a.show();
b.show();
c.show();
a.count();
b.count();
c.count();
}
Output
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value ofx=1
value ofy=1
value ofx=2
value ofy=1
value ofx=3
value ofy=1
Note: In the above figure we
have a two object (object 1 & object 2) we object occupies a separate
memory for variable(for ex: for variable 1 , object1 and object2 both will
occupy the memory) . But when a variable declared as a static then only one
memory location is occupy for all object.
Static function
In C++ programming we can create a static function by
placing the “static” keyword before the function declaration .
A static function can only assess static member variable and
member function.
In a C++ it is also possible to call a static member function without object.
Static public member
function:
Example: WAP to declare public member function and call them from main().
In a C++ language An inline function is similar to macros. Inline
function is also called as open subroutine because their code is replaced at
the place of function call in the caller function.
In a
C++programming normal function
are known as closed subroutine
because when such function are called ,the control passed to the function.
inline
function reduces the overhead of accessing the member
function, increases the efficiency of program and allows quick execution of
function.
Example of inline function
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#include <iostream>
using namespacestd;
classDemo{
public:voidshow();
voiddisplay();
};
inlinevoidDemo::show()// outside inline function
{
cout<<"Inside Show";
}
voidDemo::display()// normal function
{
cout<<"\n Inside display";
}
intmain(){
Demo obj;
obj.show();
obj.display();
}
Output
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Inside Show
Inside display
Note: 1 Inline function used when the member function contains few statement. 2 If function takes more time to execute , then it must be declared inline. .
In a
C++, we can use the function within the
classes. These functions are called as a member function. It can be public
,private & protected.
Public member function: in a below program we have created a public function which can be accessed from outside of class.
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#include <iostream>
using namespacestd;
classExample{
public:
voidshow(){// pubic member function
cout<<"inside show";
}
};
intmain(){
Example ob;
ob.show();//call to function show
return0;
}
Output
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inside show
Private member function: in a below program we have created a private function which can’t be accessed from outside of class.
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#include <iostream>
using namespacestd;
classExample{
private:
voidshow(){// private member function
cout<<"inside show";
}
};
intmain(){
Example ob;
ob.show();//error , show() is a private member function and can’t be accessed outside of class
return0;
}
Output
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error
Description: when we compile this program we will get an error message. Because show() function cant be access from main() because it is a private member function.
How to access
private member function
We can access private member function from public member function. In the below program we have created one public function display() and one private function show() and we can call the show() from within the display().
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#include <iostream>
using namespacestd;
classExample{
private:
voidshow(){// private member function
cout<<"inside show"<<endl;
}
public:
voiddisplay(){// pubic member function
show();// call to private member function show()
cout<<"inside display";
}
};
intmain(){
Example ob;
// ob.show(); //error
ob.display();
return0;
}
Output
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inside show
inside display
Define a
member function outside of the class
In a
C++ language we can define a function inside
as well as outside of the class. To define a function a function outside
of the class syntax is:
Syntax:
Datatype class_name :: function name
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#include <iostream>
using namespacestd;
classDemo{
public:voidshow();
voiddisplay();
};
voidDemo::show()// define a function show() outside of class
{
cout<<"Inside Show";
}
voidDemo::display()// define a function display() outside of class
{
cout<<"\n Inside display";
}
intmain(){
Demo obj;
obj.show();
obj.display();
}
Output
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inside show
inside display
In the above program we have declare two function inside class and define outside of the class.
a private
member function outside of the class
In a below program we have define a private function display() outside of the class which can’t be accessed from outside of class. If we try to access then we will get an error message.
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#include <iostream>
using namespacestd;
classDemo{
public:voidshow();
private:voiddisplay();
};
voidDemo::show()// define a function show() outside of class
{
cout<<"Inside Show";
}
voidDemo::display()// error, display is private function
{
cout<<"\n Inside display";
}
intmain(){
Demo obj;
obj.show();
obj.display();// error, display is private function, it can’t call from main()
}
Output
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error
Solution of above program: We can access private member function from public member function. In the below program we have created one public function show() and one private function display() and we can call the display() from within the show().
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#include <iostream>
using namespacestd;
classDemo{
public:voidshow();
private:voiddisplay();
};
voidDemo::show()// define a function show() outside of class
{
cout<<"Inside Show";
display();// call display function from show()
}
voidDemo::display(){
cout<<"\n Inside display";
}
intmain(){
Demo obj;
obj.show();
}
OUTPUT
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Inside Show
Inside display
Access Private Data Member/Variable
In a C++ we can access private data member within the class. It can’t be used outside of the class.
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classDemo{
private:intx,y;
};
intmain(){
Demo obj;
obj.x=10;// error x is not accessible hear
obj.y=20;// error y is not accessible hear
cout<<"sum ="<<(obj.x+obj.y);// error x & y are not accessible hear
}
Output
1
Error
Note: we can’t
access private data member outside of the class. The private data can be
accessed by only member function and friend
function of that class.
Solution of above program: The private data can be accessed by only member function and friend function of that class.
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#include <iostream>
using namespacestd;
classDemo{
public:voidinput();
voiddisplay();
private:intx,y;
};
voidDemo::input(){
cout<<"Enter value for x";
cin>>x;// access private data “x” in public function
cout<<"\n Enter value for y";
cin>>y;
}
voidDemo::display()// access private data “x” in public function
{
cout<<"\n value of x="<<x;
cout<<"\n value of y="<<y;
}
intmain(){
Demo obj;
obj.input();
obj.display();
return0;
}
Output
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Enter value forx
5
Enter value fory
6
value ofx=5
value ofy=6
Example. Write a C++ program to create a class and member function & find the factorial of the number given by user.
In a C++ language there are three types of access specifiers . They are: public private and protected.
Public: A public data can be accessed by out side of the code in which it is defined .
Private : A private data can not be accessed by outside of the code in which it is defined. The private data can be accessed by only member function and friend function of that class.
Protected : A protected access specifier is similar to the private only difference is that it has a access to their derived classes.
Default : By default access specifier is private means when we have not specified access specifier it will be private.
Syntax for declaring a class:
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classclass_name{
private:declaration of data members;
public:declaration of data members;
declaration of members functions;
};
Example
C
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classstudent{
private:intage;
charname[20];
public:voidinput();
voidshow();
};
In the above example we have created a new class “student”.
Inside the student class we have created two private data member age &
name[20] and two public member function input() & show().
Example : write a program to add two number by using class and public data member.
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#include <iostream>
using namespacestd;
classexample// create a new class “example”
{
public:
intx,y;//declared two public data members
};
intmain(){
example obj;// create a object “obj” of class example
obj.x=10;// by using (.) dot operator and obj initializing the variable x
obj.y=20;// by using (.) dot operator and obj initializing the variable y
cout<<"sum = "<<(obj.x+obj.y);// adding value of x and y and print
return0;
}
Output:
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sum=30
Note: In the
above program we have created a class “example” which hold public integer data
x,y and inside the main function we create a object of class example name obj.
By using the object and (.) dot operator you can access public data member of
the calss.
Note: we can
create more than one object of the class. For example:
More than one
object of the class:
in a C++ we can create one or more than one object of the class. In the below example we have created two object of class “example”.
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#include <iostream>
using namespacestd;
classexample// create a new class “example”
{
public:
intx,y;
};
intmain(){
example obj1;// create a object “obj1” of class example
example obj2;// create a object “obj2” of class example
obj1.x=10;// by using (.) dot operator and obj1 initializing the variable x
obj1.y=20;// by using (.) dot operator and obj1 initializing the variable y
obj2.x=100;// by using (.) dot operator and obj2 initializing the variable x
obj2.y=200;// by using (.) dot operator and obj2 initializing the variable y
Class: A class is a user defined data type which
contains the data members and member function. A class forms the basis for
object oriented programming.
It describes the
shape and nature of the object .Any concept that we want to implement in oop’s
must be encapsulated in class.
The internal data of the class are called data members and
functions are called member functions.
The variable of the class are called object or instance of
the class.A class is a template for
an object and an object is an instance for a class.
Syntax for declaring a class:
C++
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classclass_name{
private:declaration of data members;
public:declaration of data members;
declaration of members functions;
};
Example
C++
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classstudent{
private:intage;
charname[20];
public:voidinput();
voidshow();
};
In the above example we have created a new class “student”.
Inside the student class we have created two private data member age &
name[20] and two public member function input() & show().
Object: we can
access data members and member function outside of the class by using the
object. Object is a run time entity.
Syntax for object
creation:
Class_name object_name;
Example: student
obj;
Note: Here student is a name of the class and “obj”
is a name of the object.
Note: we can
create more than one object of the class. Foe example:
Note: By using
the object and (.) dot operator you can
access public data member of the calss.
In a C++
programming language, variable is used to hole the value & this variable
stored in a memory. Each variable has a
address to identify where these variables actually stored in a memory.
In a C++
programming language, pointer is a variable which can hold the address
of another variable.
Accessing Address of Variable
In a system every memory location has its address & we can access the address using ampersand (&) operator. This ampersand (&) operator denotes an address in memory.
Ex: int i = 20; char c = ‘a’;
In the above example, there are two variable i & c. Integer variable “i” stores the value 10 at memory location 1024(for example) and character variable “c” stores the value ‘a’ at memory location 1026.
cout<<“\n value of variable i= “<< i ; cout<<“\n value of variable c= “<< c ;
Output
value of variable i= 20 value of variable c= a
If we want to print the address of
variable ‘i and c’ then we need ampersand
(&) operator .
cout<<“\n Address of variable i = “<< &i ; cout<<“\n Address of variable c= “<< &c ;
Output: Address of variable i = 1024 Address of variable c= 1026
Note: When you run this program, address are printed might be different.Example: Write a program to print the address of the variable.
#include
using namespace std;
C++
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intmain(){
intv1;
intv2;
floatv3;
cout<<"\n Address of variable v1= "<<&v1;
cout<<"\n Address of variable v2= "<<&v2;
cout<<"\n Address of variable v3= "<<&v3;
return0;
}
Output
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Address of variable v1=0x7ffdd72d170c
Address of variable v2=0x7ffdd72d1710
Address of variable v3=0x7ffdd72d1714
Note:
Each and every time when you run this program these variables stored in a
different memory location.
Pointer
Variable
pointer variable is hold the address of another variable.
C++
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#include <iostream>
usingnamespacestd;
intmain(){
inti=20;// declare & initialize variable i
int*ptr;// declare a pointer variable ptr
ptr=&i;// ptr (pointer variable) holds the address of variable i.
cout<<"\n Address of variable i = "<<&i;
cout<<"\n Address of variable i = "<<ptr;
return0;
}
Output
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Address of variablei=0x7fff9a23444c
Address of variablei=0x7fff9a23444c
Value at address
In
the above example, there are two variable, first is normal variable ‘i’ &
pointer variable ‘ptr’. Integer variable “i” stores the value 10 at memory
location 1024(for example) and pointer variable “ptr” stores the address of
variable ‘i’ at memory location 3045.
Example:
#include
C++
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usingnamespacestd;
intmain(){
inti=10;// declare & initialize variable i
int*ptr;// declare a pointer variable ptr
ptr=&i;// ptr (pointer variable) holds the address of variable i.
cout<<"\n value of variable i= "<<*ptr;
return0;
}
Output:
value of variable i= 10
Note:
Pointer variable “ptr” prints the address of variable and “*ptr” prints the
value of i. *variable name (*ptr) is also called value at address.
Example:
C++
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#include <iostream>
usingnamespacestd;
intmain(){
inta=4;
int*b;
b=&a;
cout<<"Address of a = "<<&a;
cout<<"\n Address of a = "<<b;
cout<<"\n Address of b = "<<&b;
cout<<"\n Value of b ="<<b;
cout<<"\n Value of a = "<<a;
cout<<"\n Value of a = "<<*(&a);
cout<<"\n Value of a = "<<*b;
return0;
}
Output
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Address ofa=2464
Address ofa=2464
Address ofb=2466
Valueofb=2464
Valueofa=4
Valueofa=4
Valueofa=4
Note: When you run this program, address are printed might be different.
Pointer to Pointer
In a C
language, a pointer is an address. Normally, a pointer variable contains the
address of a another variable.
A
pointer to a pointer is a chain of pointers.
Or
Pointer to pointer means one pointer variable holds the address of another pointer variable.
Example:
C++
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#include <iostream>
usingnamespacestd;
intmain(){
inta=4;
int*b,**c;
b=&a;
c=&b;
cout<<"Address of a = "<<&a;
cout<<"\n Address of a = "<<b;
cout<<"\n Address of a = "<<*c;
cout<<"\n Address of b = "<<&b;
cout<<"\n Address of b = "<<c;
cout<<"\n Address of c ="<<&c;
cout<<"\n Value of c = "<<c;
cout<<"\n Value of c = "<<*(&c);
cout<<"\n Value of b = "<<b;
cout<<"\n Value of b = "<<*(&b);
cout<<"\n Value of b = "<<*c;
cout<<"\n Value of a = "<<a;
cout<<"\n Value of a = "<<*(&a);
cout<<"\n Value of a = "<<*b;
cout<<"\n Value of a = "<<**c;
return0;
}
Output
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Address ofa=2464
Address ofa=2464
Address ofa=2464
Address ofb=2466
Address ofb=2466
Address ofc=2468
Value ofc=2466
Value ofc=2466
Value ofb=2464
Value ofb=2464
Value ofb=2464
Value ofa=4
Value ofa=4
Value ofa=4
Value ofa=4
NULL Pointers
A
pointer that is assigned NULL is called a null pointer. We must initialize NULL pointer during
variable declaration.
A null pointer refers
to pointer variable that does not point to a valid address.
Generally NULL pointer is used when you do not have an exact address to be assigned.
Arrays is a kind of data structure that can store a elements
of the same type. Arrays stores the elements in a contiguous memory locations.
Array is a collection of variables of the same type.
For example: we want to declare 100 integer
variable
Instead of declaring 100 individual variables, such as
int number0,
number1,number2,number3, … …., number99;
you declare one integer array variable such as
int number[100];
here number[100]
is an integer array of size 100, means this array can store 100 integer value.
Array indexing starts from index 0 to n-1. Means first integer number store in array number[0], second integer number store in array number[1], third integer number store in array number[2], and so on. Here 100th number store in array numbers[99].
Array In C++
Declaring Arrays
Syntax of declare an
array in C:
Data_type arrayName [ arraySize ];
This is called a single-dimensional array.
The arraySize must
be an integer constant greater than zero.
datatype can be any valid C data type.
Example: write a program to create integer array and store 5 integer number and print.
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#include <iostream>
using namespacestd;
intmain(){
intnum[5];// array num can store 5 integer value
num[0]=20;// store 20 at array index 0
num[1]=11;// store 11 at array index 1
num[2]=20;// store 20 at array index 2
num[3]=33;// store 33 at array index 3
num[4]=55;// store 55 at array index 55
cout<<"\n num[0] = "<<num[0];
cout<<"\n num[1] = "<<num[1];
cout<<"\n num[2] = "<<num[2];
cout<<"\n num[3] = "<<num[3];
cout<<"\n num[4] = "<<num[4];
}
Output
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num[0]=20
num[1]=11
num[2]=20
num[3]=33
num[4]=55
Element Position in Array
Description : In the above program, “int num[5]” array can store 5 element in a contiguous memory locations from index 0 to 4.
Example:Write a program to take 5 number from user and store integer number in integer array and print.
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#include <iostream>
using namespacestd;
intmain(){
inti;
intnum[5];// array num can store 5 integer value
cout<<"Enter 5 integer number";
for(i=0;i<5;i++)// for loop to take 5 integer number from user
{
cin>>num[i];
}
cout<<"\n Entered number are";
for(i=0;i<5;i++)// for loop to take 5 integer number from user
{
cout<<"\n num["<<i<<"] ="<<num[i];
}
return0;
}
Output
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Enter5integernumber
Entered number are
num[0]=4
num[1]=6
num[2]=7
num[3]=8
num[4]=9
Another way to Initialize Array
We can also initialize array by this way:
int num[5] = { 54 , 4, 13,
2, 17 };
above integer array num[5], stores five numbers. Where num[0] store 54, num[1] store 4….. , & num[4] store 17.
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#include <iostream>
using namespacestd;
intmain(){
inti;
intnum[5]={
54,
4,
13,
2,
17
};
cout<<"\n Entered number are";
for(i=0;i<5;i++)// for loop to take 5 integer number from user
{
cout<<"\n num["<<i<<"] ="<<num[i];
}
return0;
}
Output
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Entered number are
num[0]=54
num[1]=4
num[2]=13
num[3]=2
num[4]=17
Multi-dimensional Arrays
C++ programming
language also support multidimensional arrays.
Syntax of multidimensional array declaration:
Data_type array_name[size1][size2]…[sizeN];
For example, if we want to creates a three dimensional
integer array −
int num[5][10][4];
Two-dimensional Arrays
The simplest form of multidimensional array
is the two-dimensional array. if we want to declare a two dimensional integer
array of size [x][y] ( where x is a number
of rows and y is a number of columns ) you would write something as follows −
int
a[3][4];
In the above line we have created two-dimensional integer array ”a” with 3 rows and 4 columns.
Two Dimensional Array
Initializing Two-Dimensional Arrays
In a C++ programming language Multidimensional arrays may be initialized by specifying bracketed values for each row. For example we want to create an integer array with 3 rows and each row has 4 columns.
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inta[3][4]={
{1,2,3,4},/* for row index 0 */
{5,6,7,8},/* for row index 1 */
{9,10,11,12}/* for row index 2 */
};
Above
the nested braces indicates the intended rows.
The
following initialization is equivalent to the previous example −
int a[3][4] = {1,2,3,4,5,6,7,8,9,10,11,12};
which indicate the nested braces for intended row, are optional.
Accessing Elements of Two-Dimensional
Array
Create a two-dimensional array of size 3*3 and nested loop is used to handle a two-dimensional array −
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#include <iostream>
using namespacestd;
intmain(){
/* an array with 3 rows and 3 columns*/
inta[3][3]={
{
1,
2,
3
},
{
4,
5,
6
},
{
7,
8,
9
}
};
inti,j;
/* output each array element's value */
for(i=0;i<3;i++){
for(j=0;j<3;j++){
cout<<"\n a["<<i<<"]["<<j<<"] ="<<a[i][j];
}
}
return0;
}
Output
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a[0][0]=1
a[0][1]=2
a[0][2]=3
a[1][0]=4
a[1][1]=5
a[1][2]=6
a[2][0]=7
a[2][1]=8
a[2][2]=9
Example: Write a program to create 3*3 matrix and take all elements of matrix as an input from user and print it.
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#include <iostream>
using namespacestd;
intmain(){
/* an array with 5 rows and 2 columns*/
inta[3][3];
inti,j;
cout<<"Enter 9 elements of 3*3 matrix in sequence";
for(i=0;i<3;i++)/* input each array element's value */{
for(j=0;j<3;j++){
cin>>a[i][j];
}
}
cout<<"Elements of 3*3 matrix is \n";
/* output each array element's value */
for(i=0;i<3;i++){
for(j=0;j<3;j++){
cout<<a[i][j]<<" ";
}
cout<<"\n";
}
return0;
}
Output
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Enter9elements of3*3matrix insequence
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2
3
4
5
6
7
8
9
Elements of3*3matrix is
123
456
789
Addition of Two Matrix
Example: Write a program to add
two matrix. Firstly, ask from user order of matrix( number of rows and column).
Then take the elements of matrix from user as a input and print the resultant
matrix
For example, if a user input
order as 3,3, i.e., three rows and three columns and
First matrix
1 2 3 4 5 6 7 8 9
Second matrix:
9 8 7 6 5 4 3 2 1
then the output of the program
(addition of the two matrices) is:
10 10 10 10 10 10 10 10 10
Matrix addition program in C++
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#include <iostream>
using namespacestd;
intmain(){
intm,n,i,j,f[10][10],s[10][10],sum[10][10];
cout<<"Enter the number of rows and columns of matrix\n";
cin>>m>>n;
cout<<"Enter the elements of first matrix\n";
for(i=0;i<m;i++){
for(j=0;j<n;j++){
cin>>f[i][j];
}
}
cout<<"Enter the elements of second matrix\n";
for(i=0;i<m;i++){
for(j=0;j<n;j++){
cin>>s[i][j];
}
}
cout<<"Sum of matrices= \n";
for(i=0;i<m;i++){
for(j=0;j<n;j++){
sum[i][j]=f[i][j]+s[i][j];
cout<<sum[i][j];
}
cout<<"\n";
}
return0;
}
Output
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Enter the number of rows andcolumns of matrix
3// enter by user
3// enter by user
Enter the elements of first matrix
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2
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8
9
Enter the elements of second matrix
9
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5
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3
2
1
Sum of matrices=
101010
101010
101010
Matrix multiplication
Example: Write a program to multiply two matrix. Firstly, ask from user order of matrix( number of rows and column). Then take the elements of matrix from user as a input and print the resultant matrix.
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#include <iostream>
using namespacestd;
intmain(){
intm,n,p,q,i,j,k,sum=0;
intf[10][10],s[10][10],multiply[10][10];
cout<<"Enter the number of rows and columns of matrix\n";
cin>>m>>n;
cout<<"Enter the elements of first matrix\n";
for(i=0;i<m;i++){
for(j=0;j<n;j++){
cin>>f[i][j];
}
}
cout<<"Enter the number of rows and columns of matrix\n";
cin>>p>>q;
if(n!=p){
cout<<"The matrices can't be multiplied with each other.\n";
In a C++ programming language a function is a
group of statements that together perform a special task. Every C++ program has
at least one function, which is main().
In a C++ library has a numerous predefined or
built-in functions. For example, strcat() to concatenate two strings, main()
from where program execution starts.
In a C++ programming function has a 3 part:
Function
declaration
Function
definition
Function
call
Note: In a C++ program we can remove the function
definition but we must place the function definition before the main() function.
Function declaration : function declaration tells the compiler about a function’s
name, return type, and parameters.
A syntax of function declaration –
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return_type function_name(parameter list);
Example of the
function declaration is as follows −
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intmax(intnum1,intnum2);
here int is a return type of function which tells function
will return integer value and max is a name of the function. “ int num1, int num2” is a parameter list which tells max
function will receive two integer arguments. Arguments are optional which depends
on program requirements.
Function definition : function definition is an actual body of the function.
Syntax of function definition:
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return_type function_name(parameter list)
{
body of the function
}
function definition consist a return type, function name,
parameter list and body of the function.
Function call :
whenever program calls a function, the
flow of control is transferred to the called function definition. A called
function performs a defined task and when flow of control reached to
function-ending closing brace, flow of control returns to back to the main
program.
Example of a user defined function.
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#include <iostream>
using namespacestd;
voidDemoFunction();// Function declaration
intmain()// The main method
{
DemoFunction();// call the function
return0;
}
voidDemoFunction()// Function definition
{
cout<<"Hello Aditya";
}
Output
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Hello Aditya
Description: Program execution start from main() function. In main() when DemoFunction(); executes it calls and transfer control to the function definition. Then statements of DemoFunction() execute and print “Hello Aditya”.
Note: In a C++ function can be called multiple times.
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#include <iostream>
using namespacestd;
voidDemoFunction();// Function declaration
intmain()// The main method
{
DemoFunction();// call the function
DemoFunction();// call the function
DemoFunction();// call the function
return0;
}
voidDemoFunction()// Function definition
{
cout<<"Hello Aditya \n";
}
Output
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Hello Aditya
Hello Aditya
Hello Aditya
Note: In a C++ program we can remove the function definition but we must place the function definition before the main() function.
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#include <iostream>
using namespacestd;
voidDemoFunction()// Function definition
{
cout<<"Hello Aditya";
}
intmain()// The main method
{
DemoFunction();// call the function
return0;
}
Output
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Hello Aditya
User-defined
function can’t declared after the main()
In a C++ program we can remove the function definition but we must place the function definition before the main() function. If we place the function definition after main() then we will get the error message. Because in a C++ execution occurs from top-to-bottom and if the function is not declared above main(), the program is unaware of it.
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#include <iostream>
using namespacestd;
intmain()// The main method
{
DemoFunction();// call the function
return0;
}
voidDemoFunction()// Function definition
{
cout<<"Hello Aditya";
}
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error:‘DemoFunction’was notdeclared inthisscope
Categories of function
We can
categories the function as:
Function
with no argument, no return value
Function
with argument but no return value
Function
with argument and return value
Function
with no argument, but return value
Function with no
argument & no return value
Example: Write a program to find the area of
circle using function with no argument, no return value.
The formula for the area of the circle is :
Area_circle = Π * r * r
Program:To calculate Area of Circle
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#include <iostream>
using namespacestd;
voidareaOfcircle();//Function declaration
intmain(){
areaOfcircle();// Function Call
return0;
}
voidareaOfcircle()// function definition to calculate area of circle
{
floatarea,radius;
cout<<"Enter the radius of circle : ";
cin>>radius;// take radius as input
area=3.14*radius *radius;
cout<<"\n Area of circle= : "<<area;
}
Output
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Enter the radius of circle
5// enter by user
Area of circle=78.50
Function with argument
but no return value
Example: Write a program to find the area of circle using function with argument but no return value.
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#include <iostream>
using namespacestd;
voidareaOfcircle(floatr);//Function declaration
intmain(){
floatradius;
cout<<"Enter the radius of circle : ";
cin>>radius;// take radius as input
areaOfcircle(radius);// Function Call
return0;
}
voidareaOfcircle(floatr)// function definition to calculate area of circle
{
floatarea;
area=3.14*r *r;
cout<<"\n Area of circle= : "<<area;
}
Output
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Enter the radius of circle
5// enter by user
Area of circle=78.50
Function with argument
& return value
Example: Write a program to find the area of circle using function with argument but return value.
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#include <iostream>
using namespacestd;
floatareaOfcircle(floatr);//Function declaration
intmain(){
floatradius,a;
cout<<"Enter the radius of circle : ";
cin>>radius;// take radius as input
a=areaOfcircle(radius);// Function Call
cout<<"\n Area of circle= : "<<a;
return0;
}
floatareaOfcircle(floatr)// function definition to calculate area of circle
{
floatarea;
area=3.14*r *r;
returnarea;
}
Output
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Enter the radius of circle
5// enter by user
Area of circle=78.50
Function with no argument but return value
Example: Write a program to find the area of circle using function with no argument but return value.
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#include <iostream>
using namespacestd;
floatareaOfcircle();//Function declaration
intmain(){
floata;
a=areaOfcircle();// Function Call
cout<<"\n Area of circle= : "<<a;
return0;
}
floatareaOfcircle()// function definition to calculate area of circle
{
floatradius,area;
cout<<"Enter the radius of circle : ";
cin>>radius;// take radius as input
area=3.14*radius *radius;
returnarea;
}
Output
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Enter the radius of circle
5// enter by user
Area of circle=78.50
Call
by value & Call by reference
Call by value : Whenever we call a function and passes the value of variable to the called function is called call by value.
C++
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#include <iostream>
usingnamespacestd;
voidswap(inta,intb){
inttemp;
temp=a;
a=b;
b=temp;
}
intmain(){
inta=10,b=20;
cout<<"Value of a & b before swap="<<a<<" "<<b<<endl;
swap(a,b);// passing value to function
cout<<"Value of a & b after swap="<<a<<" "<<b;
return0;
}
Output
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Value ofa&bbefore swap=1020
Value ofa&bafter swap=1020
Call by reference : Whenever we call a function and passes the reference of variable to the called function is called call by reference. In the call by reference, to pass the reference of the variable we use pointer.
C++
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#include <iostream>
usingnamespacestd;
voidswap(int*x,int*y){
intswap;
swap=*x;
*x=*y;
*y=swap;
}
intmain(){
intx=10,y=20;
cout<<"Value of x & y before swap=: "<<x<<" "<<y<<endl;
swap(&x,&y);// passing reference/ address of variable to function
In
the C++ language decision making statement executes if the given condition
is true otherwise conditional block will
never execute.
C++ language assumes non-zero and non-null values as true, and zero or null
is assumed as false value.
There are following types of decision making statements in C++ programming language.
if statement
Syntax of an ‘if’ statement −
if(Condition) { /* statement will execute if the condition is true */ }
In a ‘if’ statement if the Condition is true, then the block of statement of the ‘if’ statement will be executed. If the Condition is false, then the block of statement of the ‘if’ statement will not executed and control sent to the next line of if block.
Example: Write a program to demonstrate the ‘if’ statement.
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#include <iostream>
using namespacestd;
intmain()
{
intx=10;
inty=25;
if(x<y)// condition x < y is true therefore if block will execute
{
cout<<"Sum of x+y = "<<(x+y);
}
cout<<"\n after if statement";
return0;
}
Output
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Sum ofx+y=35
after ifstatement
In the above program if reverse the ‘if’ condition of ‘if’ statement then the condition will be false and ‘if’ block will never execute.
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#include <iostream>
using namespacestd;
intmain()
{
intx=10;
inty=25;
if(x>y)// condition x>y is false therefore if block will not execute
{
cout<<"Sum of x+y = "<<(x+y);
}
cout<<"\n after if statement";
return0;
}
Output
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after ifstatement
if-else statement
Syntax of an ‘if-else’ statement −
if(Condition) { /* if-statement will execute if the Condition is true */ } else { if the condition is false then else block will execute }
In a ‘if-else’ statement if the Condition is true, then the block of statements of the ‘if’ statement will be executed. If the Condition is false, then the block of code of the ‘else’ statement will executed.
Example: Write a program to take two numbers from user and find the grater between them using ‘if-else’ statement.
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#include <iostream>
using namespacestd;
intmain()
{
intx;
inty;
cout<<"enter 1st number";
cin>>x;// 10
cout<<"\n enter 2nd number";
cin>>y;// 30
if(x>y)// check condition x>y
{
cout<<"\n grater value= "<<x;
}
else
{
cout<<"\n grater value= "<<y;
}
return0;
}
Output
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1stnumber10// user enter 10 in variable x enter 2nd number 30 // user enter 30 in variable y grater value= 30
Nested -if statement In a C language we can use if statement inside another if statement(s). Syntax of an ‘nested -if’ statement −
if(condition 1) { /* statement will execute if the condition 1 is true */ If (condition 2) { /* statement will execute if the condition 2 is true */ } }
Example: Write a program to take two numbers from user if both number are between 1 to 9 then print “Good” using nested-if statement.
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#include <iostream>
using namespacestd;
intmain()
{
intx;
inty;
cout<<"enter 1st number";
cin>>x;// 5
cout<<"\n enter 2nd number";
cin>>y;// 7
if(x<10)// check condition x < 10
{
if(y<10)// nested-if, check condition y < 10
{
cout<<"\n Good";
}
}
return0;
}
Output
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enter1stnumber5// user enter 5 in variable x enter 2nd number 7 // user enter 7 in variable y Good
Nested if-else
statements
In a C language we
can use if or if-else statement inside another if or
if-else statement(s).
Syntax of an ‘if-else’ statement −
if(condition 1) { /* statement will execute if the condition 1 is true */ If (condition 2) { /*if- statement will execute if the condition 1 & 2 both are true */ } else { /* else-statement will execute if the condition1 is true Condition2 is false */ } } else { If (condition 3) { /* statement will execute if the condition 3 is true */ } }
Example: Write a program to take three numbers from user and find the grater among them using ‘nested if-else’ statement.
