c++ pointers are easy and fun to learn. some c++ tasks are performed more easily with pointers, and other c++ tasks, such as dynamic memory allocation, cannot be performed without them.

as you know every variable is a memory location and every memory location has its address defined which can be accessed using ampersand (&) operator which denotes an address in memory. consider the following which will print the address of the variables defined −

#include <iostream>

using namespace std;
int main () {
   int  var1;
   char var2[10];

   cout << "address of var1 variable: ";
   cout << &var1 << endl;

   cout << "address of var2 variable: ";
   cout << &var2 << endl;

   return 0;
}

when the above code is compiled and executed, it produces the following result −

address of var1 variable: 0xbfebd5c0
address of var2 variable: 0xbfebd5b6

what are pointers?

a pointer is a variable whose value is the address of another variable. like any variable or constant, you must declare a pointer before you can work with it. the general form of a pointer variable declaration is −

type *var-name;

here, type is the pointer's base type; it must be a valid c++ type and var-name is the name of the pointer variable. the asterisk you used to declare a pointer is the same asterisk that you use for multiplication. however, in this statement the asterisk is being used to designate a variable as a pointer. following are the valid pointer declaration −

int    *ip;    // pointer to an integer
double *dp;    // pointer to a double
float  *fp;    // pointer to a float
char   *ch     // pointer to character

the actual data type of the value of all pointers, whether integer, float, character, or otherwise, is the same, a long hexadecimal number that represents a memory address. the only difference between pointers of different data types is the data type of the variable or constant that the pointer points to.

using pointers in c++

there are few important operations, which we will do with the pointers very frequently. (a) we define a pointer variable. (b) assign the address of a variable to a pointer. (c) finally access the value at the address available in the pointer variable. this is done by using unary operator * that returns the value of the variable located at the address specified by its operand. following example makes use of these operations −

#include <iostream>

using namespace std;

int main () {
   int  var = 20;   // actual variable declaration.
   int  *ip;        // pointer variable 

   ip = &var;       // store address of var in pointer variable

   cout << "value of var variable: ";
   cout << var << endl;

   // print the address stored in ip pointer variable
   cout << "address stored in ip variable: ";
   cout << ip << endl;

   // access the value at the address available in pointer
   cout << "value of *ip variable: ";
   cout << *ip << endl;

   return 0;
}

when the above code is compiled and executed, it produces result something as follows −

value of var variable: 20
address stored in ip variable: 0xbfc601ac
value of *ip variable: 20

pointers in c++

pointers have many but easy concepts and they are very important to c++ programming. there are following few important pointer concepts which should be clear to a c++ programmer −