About Me

My photo
Raipur, Chhattisgarh, India
Hi , I am Amit Thakur. I have worked as a QA Engineer for two years and as a Java Developer for one year in NIHILENT TECHNOLOGIES PVT. LTD., Pune.Currently I am working as DEAN (Research & Development) in Bhilai Institute of Technology, Raipur.

Unit-4 Pointers

Pointer to Pointer:

A pointer to a pointer is a form of multiple indirection, or a chain of pointers. Normally, a pointer contains the address of a variable. When we define a pointer to a pointer, the first pointer contains the address of the second pointer, which points to the location that contains the actual value as shown below.

A variable that is a pointer to a pointer must be declared as such. This is done by placing an additional asterisk in front of its name. For example, following is the declaration to declare a pointer to a pointer of type int:
int **var;
When a target value is indirectly pointed to by a pointer to a pointer, accessing that value requires that the asterisk operator be applied twice, as is shown below in the example:
#include

int main ()
{
   int  var;
   int  *ptr;
   int  **pptr;

   var = 3000;

   /* take the address of var */
   ptr = &var;

   /* take the address of ptr using address of operator & */
   pptr = &ptr;

   /* take the value using pptr */
   printf("Value of var = %d\n", var );
   printf("Value available at *ptr = %d\n", *ptr );
   printf("Value available at **pptr = %d\n", **pptr);

   return 0;
}
When the above code is compiled and executed, it produces the following result:
Value of var = 3000
Value available at *ptr = 3000
Value available at **pptr = 3000


No comments: