C++ Pointers

C++ pointers are special variable that contains the address of ordinary variable of its type. If you a define a pointer of float type then, it can only stores the address of float type variable. C++ pointer is very important concept. 

Pointer Notation

float a = 5.2;

The above statement tells the c++ compiler that,

(1) It reserves  a memory block, that can only contains float value.

(2) Name of that memory block is a, so we can access that memory block by variable a. 

(3) Value 5.2 is stored in that memory block.

Computer selects a memory location to store 5.2, this memory location is also known as address. 

We can store this memory location in a special variable called pointer variable.

float a = 5.2;

float *b;

b = &a;

Here b is a pointer variable that stores the memory address of variable a.

* symbol is used for declaring a pointer variable.

Value at address operator 

C++ has a pointer operator called value at address operator. It is represented as '*' operator. At the time of pointer variable declaration, it has different meaning.

Value at address operator gives the value stored at specified address. 

Value at address operator is also known as indirection operator.

See the following code:

float a = 5.2; //line 1

float *b;        //line 2

b = &a;         //line 3

cout<<*b;    //line 4

OUTPUT:

5.2

Program to Illustrate C++ Pointers

#include <iostream>

using namespace std;

int main()

{

    int a = 1;

    float b = 2.1;

    char c = 'A';

    int *p;

    float *q;

    char *r;

    cout<<"Value of a   = "<<a<<"\nAddress of a = "<<&a;

    cout<<"\nValue of b   = "<<b<<"\nAddress of b = "<<&b;

    cout<<"\nValue of c   = "<<c<<"\nAddress of c = "<<&c;

    cout<<endl<<endl;

    p = &a;

    q = &b;

    r = &c;

    cout<<"Value of a   = "<<*p<<"\nAddress of a = "<<p;

    cout<<"\nValue of b   = "<<*q<<"\nAddress of b = "<<q;

    cout<<"\nValue of c   = "<<*r<<"\nAddress of c = "<<r;

    return 0;

}

OUTPUT:

Value of a   = 1

Address of a = 0x28fef0

Value of b   = 2.1

Address of b = 0x28feec

Value of c   = A

Address of c = Aff♠@☺

Value of a   = 1

Address of a = 0x28fef0

Value of b   = 2.1

Address of b = 0x28feec

Value of c   = A

Address of c = Aff♠@☺