The pointer in c language is a variable, which stores address of another variable. Whenever we declare a variable in c, it takes some space in memory and each memory has a unique address in hexadecimal numbers.

Pointers : Key Points in C

• Normal variables stores value, and pointer variable stores address.
• The pointer in c is used to allocate memory dynamically (at run time).
• C language has two symbols ( & and *) to work with pointers.
• & – returns the address of a variable in C.
• * – returns the value of a variable, pointed by a pointer variable.
• %p – Format in c to print pointer reference.

Example 1: Print address of a variable in C language.

#include<stdio.h>
int main()
{
int n=10;
	printf("\n %d",n); // print value of n.
	printf("\n %p",&n);	//print address of n
return 0;
}

Sample Output:
10
0x7ffe676efd6c

Example 2: Declare and use of pointer variables in c language.

#include<stdio.h>
int main()
{
int n, *pt;
	n=10;
	pt=&n;
	printf("\nValue : %d", n); // print value of n.
	printf("\nAddress %p", pt);	//print address of n
	printf("\nValue : %d", *pt); // print value of n.
return 0;
}

Sample Output:
Value : 10
Address 0x7ffd90c6b3b4
Value: 10

Whenever we use a pointer variable with (*) symbol, then it refers to the variable that’s address is stored in the pointer variable.

Address of a variable will be different on your pc, and address can change every time when you run the program.

Double Pointer in C (Pointer to Pointer)

As we know that the pointer variables are used to store the address of a normal variable, to store the address of a pointer variable, we will use double pointers. Double pointers are also know as pointer to pointer in c.

Example 3: C program of double pointer implementation in C

//to declare a double pointer in c, you need to use double **.
#include<stdio.h>
int main()
{
int n,*a,**b;
	n=10;
	a=&n;
	b=&a;
	printf("\n %d",n);	//print value of n
	printf("\n %p",a);	//print address of n, 
	printf("\n %p",b);	//print address of a
	printf("\n %d",*a);	//print value of n
	printf("\n %p",*b);	//print address of n
	printf("\n %d",**b);	//print value of n
return 0;
}

sample Output:
10
0x7ffda19aee74
0x7ffda19aee78
10
0x7ffda19aee74
10

In the above code **b is same as *(*b), means *(a), because *b refers a.

Pointer with Array in C.

#include<stdio.h>
int main()
{
int n[5],i,*b;
	for(i=0;i<5;i++)
	{
		printf("\nEnter a number");
		scanf("%d",&n[i]);
	}

	b=&n[0];	//pointer points 0th element of the array

	//It will print 5 times value of 0th element only
	for(i=0;i<5;i++)
	{
		printf("%d\n",*b);	
	}

	//It will print value of array, because of increment in pointer address
	printf("Printing Array with Pointer Increment\n");
	for(i=0;i<5;i++)
	{
		printf("%d\n",*b);	
		b++;
	}

return 0;
}

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