Pointers

Pointers

A pointer are a special variable, which can stores the address of another variable.

& ampersand (address of operator)

&a => address of a

To find a address of given variable

WAP to find out address of variables

Example 1️:

#include <iostream>
using namespace std;

int main() {

    int a = 10;
    int b = 20;
    int c = 30;

    cout<<"Address of a : "<<&a<<"value"<<a<<endl;

    cout<<"Address of b : "<<&b<<"value"<<b<<endl;

    cout<<"Address of c : "<<&c<<"value"<<c<<endl;

    return 0;
}

Output :

Address of a : 0x7ffeaea3b0ec value of 10
Address of b : 0x7ffeaea3b0e8 value of 20
Address of c : 0x7ffeaea3b0e4 value of 30

Expalantion

In a Line no 6 we initialize a variable and store 10 value
In a Line no 7 we initialize b variable and store 20 value
In a Line no 8 we initialize c variable and store 30 value
In a Line no 10 print Address of a and &a, a variable.
Same as Line no 12 and 14.

Syntax

<datatype>* <variable>

int* age

WAP to store a variable address

Example 2:

#include <iostream>
using namespace std;

int main() {

    int age = 22;

    cout<<"address of age : "<<&age<<endl;

     int* address = &age;
     cout<<"address from pointer :"<<address;


    return 0;
}

Output :

address of age : 0x7ffe390d907c
address from pointer : 0x7ffe390d907c

Expalantion

In a Line no 6 we initialize age variable and store 22 value
In a Line no 8 print Address of age and &age
In a Line no 10 create pointer variable and store address of age.
In a Line no 11 print address from ponter : and address variable.

Dereference operator

If there is * symbol before the variable then it is called dereference operator.

Example 3:

#include <iostream>
using namespace std;

int main() {

    int age = 22;
    cout<<"address of age : "<<&age<<endl;

     int* address = &age;
     cout<<"address from pointer :"<<*address;


    return 0;
}

Output :

address of age : 0x7ffe390d907c
address from pointer : 22

Expalantion

In a Line no 6 we initialize age variable and store 22 value
In a Line no 8 print Address of age and &age
In a Line no 10 create pointer variable address and store address of age.
In a Line no 11 print address from ponter :and dereference *address varible.

Example : 4

#include <iostream>
using namespace std;

int main() {

    int age = 22;
    int* p = &age;

    cout<<"1) "<<&age<<endl;
    cout<<"2) "<<age<<endl;
    cout<<"3) "<<&p<<endl;
    cout<<"4) "<<p<<endl;
    cout<<"5) "<<*p<<endl;


    return 0;
}

Output :

1. 0x7ffe390d904c
   
2. 22
   
3. 0x7ffe390d904O
   
4. 0x7ffe390d904c
   
5. 22
   

Expalantion

In a Line no 7 we initialize age variable and store 22 value
In a Line no 8 create pointer variable p and store address of age.
In a Line no 10 print &age.
In a Line no 11 print age.
In a Line no 12 print &p.
In a Line no 13 print p.
In a Line no 14 print *p.