Introduction to C++:
C++ was developed by Bjarne
Stroustrup at Bell Lab in 1983. All the
keywords in C are the keywords in C++ with some new keywords. The Name C++ comes from the increment
operator of C Language. C++ is not
merely an extension of C, where some new syntax has been added basic purpose of
C++ is to add features to the standard C language supporting use to Object
Oriented Programming.
Additional Keywords in C++:
class friend virtual inline
private public protected const
this new delete operator
Comments:
Comments are the non executable
statements. In C as well as C++ // is used for single line comment and /*- -
- - - - - - - - - - - - - - - - */ is a multiple line statement comment.
Variable Declarations:
In C++ declarations of variable
can be done with executable program statements.
Example 1
#include <stdio.h>
int main(void){
int x=10;
printf(“Value of X%d\n””,x);
int y=0;
for(int z=0; z<<; z++)
{
printf(“\nz =%d”,z);
z++;
x++;
y--;
}
Scope Resolution Operator(:
:):
C++ provides the scope resolution
operator to access global variables.
Thus overriding a local variable with the same name. This operator prefixed to the name of the
global variable.
Example 2
#include<stdio.h>
int global =10;
void main ( ){
int gloabal =20;
printf(“Writing Global
Prints%d\n”,global);
printf(“Writing Global
Prints%d\n”,:: global);
}
New and Delete Operators:
New operator allocates memory for
the given size and returns a pointer to its starting point. And delete operator releases the memory which
is allocated by new e.g.
char arr[100];
arr = new char[size];
It is possible that the system
may not have enough memory available to satisfy a request by new operator and
so it returns a Null pointer. So
returned value from new should always be checked before any operator on it,
which otherwise may lead to advertent system crashes. Once memory is allocated by new operator it
can be accessed using indirection operator(*) or array subscripts.
Practical
Session 1
Example 1(WS Manipulator)
#include<conio.h>
#include<iostream.h>
#include<iomanip.h>
main(void){
char name[100];
clrscr( );
cout<<"Enter Line of
text \n " ;
cin>>ws;
cin>>name;
cout<<"Typed text
="<<name<<endl;
getch( );
}
Example 2(Set Precision
Manipulator)
#include<conio.h>
#include<iostream.h>
#include<iomanip.h>
main(void){
float a,b,c;
a=5;
b=3;
c=a/b;
clrscr( );
cout<<setprecision(1)<<c<<endl;
cout<<setprecision(2)<<c<<endl;
cout<<setprecision(3)<<c<<endl;
getch( );
}
Example 3(SetW and Sefill
Manipulator)
#include<conio.h>
#include<iostream.h>
#include<iomanip.h>
main(void){
int a,b;
a=200;
b=300;
cout<<setfill("*");
cout<<setw(5)<<a<<setw(5)<<b<<endl;
cout<<setw(6)<<a<<setw(6)<<b<<endl;
cout<<setw(7)<<a<<setw(7)<<b<<endl;
cout<<setw(8)<<a<<setw(8)<<b<<endl;
}
Example 4(Ends Manipulator)
#include<conio.h>
#include<iostream.h>
#include<iomanip.h>
main(void){
int number=123;
clrscr( );
cout<<'\"'<<"number
=" <<number<<ends;
cout<<'\"'<<endl;
getch( );
}
Example 5(Reading a String)
#include<iostream.h>
#include<conio.h>
void main(void){
char ch;
clrscr( );
cout <<"\n Enter a
Line :";
for( ; (ch =cin.get( ))!='\n'; ){
cout<<"\n Your
character is : ";
cout.put(ch);
}
getch( );
}
Example 6 (Fill and Width)
#include<iostream.h>
#include<conio.h>
void main(void){
clrscr( );
cout.width(10);
cout.fill('x');
int num=6;
cout<<num<<"\n";
cout.width(15);
cout.fill('-');
num=12345;
cout<<num<<endl;
getch( );
}
Example 7(Field Justification)
#include<iostream.h>
#include<conio.h>
void main(void){
int num =71;
clrscr( );
cout.fill('*');
cout.setf(ios::showpos);
cout.setf(ios::left,ios::adjustfield);
cout.width(6);
cout<<num<<"\n";
cout.setf(ios::right,ios::adjustfield);
cout.width(6);
cout<<num<<"\n";
cout.setf(ios::internal,ios::adjustfield);
cout.width(6);
cout<<num<<"\n";
getch( );
}
Example 8(Printing Numbers from 0
to 9)
#include<iostream.h>
#include<conio.h>
void main(void){
int i;
clrscr( );
for(i=0;i<=9;i++)
{
cout<<"\n i =
"<<i;
}
getch( );
}
Example 9(A Structure Program)
#include<iostream.h>
#include<conio.h>
#include<process.h>
struct student{
int
rollno;
char
name[25];
char
branch[30];
int
marks;
};
void main( )
{
clrscr( );
student s1;
cout<<"\n Enter
Student Data : ";
cout<<"\n Enter
Rollno : ";
cin>>s1.rollno;
cout<<"\n Enter
Student Name : ";
cin>>s1.name;
cout<<"\n Enter Study
Branch : ";
cin>>s1.branch;
cout<<"\n Enter Total
Marks : ";
cin>>s1.marks;
cout<<"\n\n\n\t\t\t\t
Student Report ";
cout<<"\n\t\t\t
***************************";
cout<<"\n Rollno
\tName \t\tBranch \t\tMarks \t\tPercent ";
cout<<"\n
"<<s1.rollno<<"\t\t"<<s1.name<<"\t\t"<<s1.branch<<"\t"<<s1.marks<<"\t\t"<<s1.marks*(100.0/325);
getch( );
}
Example 10(Calculation of
Cirmferance of a Circle)
#include<stdio.h>
#include<conio.h>
main( ){
clrscr( );
float radius,circum,area;
float pi=3.1416;
printf("\nEnter value of the
Radius :");
scanf("%f",&radius);
circum=2*pi*radius;
area=pi*radius*radius;
printf("\nThe Circumferance
of the Circle : %f",circum);
printf("\nThe Area of the
Circle : %f",area);
getch( );
}
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