Pointer (program & theory)

Pointer: is a special kind of variable that store the address of another variable nothing else, using pointer we can use the value of a variable without effecting its value, with pointer one can print the address and actual value at that adress

pointer are of many types

1. array pointer: used to store the address of whole array

2. simple pointer: used to store the address of a sigle variable

3. double pointer: used to point for pointer and its values

4. null pointer: declare  to make use  of it later

5. constant pointer: contant pointer

Program to use the concept of array pointer and a simple pointer

#include<conio.h>

#include<stdio.h>

void main()

{

    int a[6]={1,2,3,4,5,6};

    int (*p)[6];

    p=&a;

    int *b=&a[0];

    printf("%d",p);

    printf("\n %d",b);

    p++;

    b++;

    printf("\n %d",p);

    printf("\n %d",b);

}

Ouput:

Program to use constant Pointer

#include<conio.h>

#include<stdio.h>

void  main()

{

   

    int c=9;

    int v=0;

    int *const a=&c;

    printf("%d",*a);

    // a=&v;  This will through error.

}

Ouput:

Program to illustrate the concept of double pointer

#include<conio.h>

#include<stdio.h>

void  main()

{

    int *a,**b;

    int c=4;

    a=&c;

    printf(" a=%d",a);

    // *a=&c;   this will not work.

    //**b=a;this will not work.

    //**b=&a;this will not work.

    // **b=c;

    //printf(" **b=%d",**b);

    b=&a;

    printf("\nb=%d",b);//own address

    printf("b=%d",*b);//step 1 adress means (&*a)

    printf(" b=%d",**b);//step 2 value mens (c)

}

Ouput: