Pointer in CPP

 

Pointer

Pointer points address of another variable

syntex

datatype  *variablename=value;

eg. int  *a=5;

int *b=&a;

  Example:

int a;

int  *ptr;

a=10;

ptr=&a;

100     - address of a         200  -  address of  ptr

             value of a                           value of ptr

a                                                             ptr

 

-a                          refers to 10

-&a                       refers to 100

-*(&a)                  refers to 10

-ptr                       refers to 100

-&ptr                    refers to 100

-*ptr                     refers to 10

 

 

program:1

#include<iostream.h>

#include<conio.h>

void main()

{

int i,*iptr;

iptr=&i;

i=20;

clrscr();

cout<<" i value is "<<i<<endl;

*iptr=*iptr+30;

cout<<"i value is "<<i<<endl;

getch();

}

output:

i value is 20

i value is 50

 

program:2

#include<iostream.h>

#include<conio.h>

void main()

{

int arr[5]={10,20,30,40,50};

int  *ptr,i;

ptr=arr;

clrscr();

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

{

         cout<<*(ptr+i)<<"\t";

         *(ptr+i)=*(ptr+i)+5;

}

cout<<endl;

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

{

                  cout<<arr[i]<<endl;

}

getch();

}

output:

10 20 30 40 50

15 25 35 45 55

program:3

#include<iostream.h>

#include<conio.h>

void main()

{

char name[10];

char *cptr;

clrscr();

cout<<"enter the name in lower case:";

cin>>name;

cptr=name;

for(;*cptr!='\0';cptr++)

{

   if(*cptr>='a' && *cptr<='z')

                *cptr=*cptr-32;

}

cout<<" upper case is : "<<cptr<<endl;

}

output:

Enter the name in lower case : apple

Upper case is : APPLE