Basics of C++

         Revision C++

                                            By

                          Mr.Harmandeep Singh

                                        &

                               Miss.Ankita Pabbi

          Introduction to C++

Developed at AT & T Bell Lab

By Bjarne Stroustrup  

Keywords

Reserved word or system defined words. e.g.: int, long, do, while, static, public, for, if, new, delete, friend, const, auto, void etc

Identifiers

•An identifier is the name given by user for a unit of the program. E.g.: variable name, array name, function name, class name etc.

               Literals

 •Data items that never change during the execution of program.

•Types of literals:

•       Integer : e.g. : 12, 8, 78

•       Float : 2.5, 6.9

•       Character: ‘a’ , ‘c’

•       String: “anku”, “a”

•       Back Slash constant: \n \t \b \a

                Punctuators  

•{ } [ ] ( ) , ; : * = # 

                 Operators

•       Arithmetic operators: +  * / %

•       Relation operators: < > <= >=  == !=

•       Increment / Decrements: ++ --

•       Logical Operators: &&, ||,! (and, or, not)

•       Conditional: ? :

•       Shorthand: +=, -=, /=, *=

•       –Ex- a=a+b; can be write as a+=b;

           Data Types

•       Fundamental data types

•       Derived data types

              Fundamental Data types

•       int

•       char

•       float

•       double

                  

                      Data type modifiers

•       signed

•       unsigned

•       long

•       short

           Derived data type

•       Arrays

•       Function

•       Pointer

•       Reference etc.

     User Defined derived data type

•       Class

•       Structure

•       Union

•       Enumeration

              Variable

•       A name of storage location is called variable.

         Declaration of Variables

int  x, y, z;

int  a=10;

float  p,q,r;

float  z=3.5;

char a, ans=‘y’;

char name[20];

double f;

         Declaration of constants

const int MAX = 100;

const double PI = 3.14;

const char A = ‘n’;

const char name[] = “Ashok”;

          Symbolic constant

#define PI 3.14

#define MAX 100

                 

                Header Files

•       iostream.h -> cin, cout

•       stdio.h -> printf(), scanf()

•       conio.h -> getch(), clrscr()

•       string.h -> strcpy(), strcat(), strlen(), strcmp(), strlwr(), strupr()

•       ctype.h -> isdigit(), isalpha(), ….

•       math.h -> pow(), sqrt()

           

               I/O statements

•       cout -> output

•       cin   -> input

Ex-

int x;

cout<<“Enter x:”<<endl;

cin>>x;

cout<<“You entered:”<<x;

                  Character I/O

•       getchar()

•       putchar()

•       getch()

•       getche()

•       get()

•       put()

•       getline()

•       read()

•       write()

Single statement vs compound

Statement

•       Single statement write simple manner

•       Compound statement is enclosed in { }

        Control Structure

•       Sequence

•       Selection

•       looping

         SELECTION

•       simple if

•       if else

•       if else if ladder

•       switch

               if statement

Syntax:

 if (condition )

     expression;

Ex-

if (age<21)

cout<<“You are not eligible for marriage”;

              if else

Syntax:-

if( condition )

     expression1;

else

     expression2;

Ex:-

if( age<=21 )

     cout<<“ You are eligible for marriage”;

else

      cout<<“ You are not eligible for marriage”;

       if else if ladder statement

if(condition)

     Expression1;

else if(condition)

     Expression2;

else if(condition)

     Expression3;

…….

else

     Default Expression;

if(per>=75)

     cout<<“honor”;

else if(per>=60)

      cout<<“First”;

else if(per>=45)

      cout<<“Second”;

else if(per>=33)

      cout<<“Pass”;

else

     cout<<“Fail”;

         Switch Statement

switch(index)

{

case1:statement1; break;

case2:statement2; break;

case3:statement3; break;

…........

default;

 default statement;

}

                  Switch contd.

switch(choice)

{

case 1: c=a+b; break;

case2: c=a-b; break;

case3: c=a*b; break;

case4: c=a/b; break;

default:

  cout<<”invalid choice”;

}

   Looping Statements

•       while        -> Entry control

•       for            -> Entry control

•       do ….. while -> Exit Control

                 While

syntax:

Initialization;

while(condition)

{

//body of loop;

      //inc/dec

           }

     Ex:

int c=1;

while(c<=100)

{

cout<<c<<emdl;

c=c+1;

}

                do while

syntax:

Initialization;

do

{

//body of loop

//inc/dec

}while(condition);

Ex:

int c=1;

do

{

cout<<c<<endl;

c=c+1;

}while(c<=100);

                for

Syntax:

for(Initialization;condition;increment)

{

//body of loop;

}

Ex:

for(c=1;c<=100;c++)

{

cout<<c<<endl;

}

           Nesting of Loop

•       When we use one loop structure into another loop structure it is called nesting of loop.

                     Array

An array is a collection of variables of the same type that are referenced by a common name.

Types of an array:-

•       One dimensional

•       Two dimensional

             Declaration of an array

Single dimensional:

data_type    arrayname[size];

Ex-

int  a[10];

float q[20];

char name[10];

        Two dimensional array:

data_type   arrayname[rowsize][colsize];

Ex:-

int   mat[3][3];

char  name[20][10];

                   Reading of an array

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

{

cin>>a[i];

}

   Display of an array element on screen

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

{

cout<<a[i]<<endl;

}

          Reading 2D array

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

{

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

{

cout<<mat[i][j]<<“ “;

}

cout<<endl;

}

      

          Display 2D array on screen

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

{

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

{

cout<<mat[i][j]<<“ “;

}

cout<<endl;

}

               Thanks…….