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Explain the concept of Array of Pointer and Pointer to Pointer in C programming
Array Of Pointers
Just like any other data type, we can also declare a pointer array.
Declaration
datatype *pointername [size];
For example, int *p[5]; //It represents an array of pointers that can hold 5 integer element addresses
Initialization
The ‘&’ is used for initialization
For example,
int a[3] = {10,20,30};
int *p[3], i;
for (i=0; i<3; i++) (or) for (i=0; i<3,i++)
p[i] = &a[i];
p[i] = a+i;Accessing
Indirection operator (*) is used for accessing.
For example,
for (i=0, i<3; i++)
printf ("%d" *p[i]);Example
#include<stdio.h>
main (){
int a[3] = {10,20,30};
int *p[3],i;
for (i=0; i<3; i++)
p[i] = &a[i]; //initializing base address of array
printf (elements of the array are”)
for (i=0; i<3; i++)
printf ("%d \t", *p[i]); //printing array of pointers
getch();
}Output
elements at the array are : 10 20 30
Pointer to Pointer
Pointer to pointer is a variable that holds the address of another pointer.
Declaration
datatype ** pointer_name;
For example, int **p; //p is a pointer to pointer
Initialization
The ‘&’ is used for initialization.
Eg −
int a = 10; int *p; int **q; p = &a;
Accessing
Indirection operator (*) is used for accessing.
Example
#include<stdio.h>
main (){
int a = 10;
int *p;
int **q;
p = &a;
q = &p;
printf("a =%d",a);
printf("a value through pointer = %d", *p);
printf("a value through pointer to pointer = %d", **q);
}Output
a=10 a value through pointer = 10 a value through pointer to pointer = 10
Updated on: 09-Mar-2021
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