Pointers in C++

Pointers are used to solve many problems in C++. Some C++ tasks are performed more easily with pointers, and other C++ tasks, such as dynamic memory allocation, cannot even be performed without the use of pointers.

As we already know that a 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. 

Let us consider the following code which will print the address of the variables defined –

#include <iostream>
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;
}

Output:

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

A pointer is a variable whose value is the address of another variable. Like any variable or constant, in C++ 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. 

Here 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, all the pointers return a long hexadecimal number that represents the memory address of the variable as shown in the above example. 

The only difference between pointers of different data types is the data type of the variable or constant that the pointer points to.