What are Pointers?

Pointer is a variable that points to an address of a value.

Pointer => address that contains the value

Symbols used in pointer :

& (ampersand sign) : ‘Address of operator’. It determines the address of a variable.

* (asterisk sign) : indirection operator / value at address. Accesses the value at the address.

Example :

    int i = 3 ;

This declaration tells the C compiler to :-

• Reserve space in memory to hold the integer value.
• Associate the name i with this memory location.
• Store the value 3 at this location.

We may represent the location of i in the memory by :-

• The computer has selected memory location 65524 as the place to store the value 3.
• The location number 65524 is not a number to be relied upon, because some other time the computer may choose a different location for storing the value 3.
• The important point is, i’s address in memory is a number.

Example :

    #include <stdio.h>
    #include <conio.h>

    void main()
    {
    int i = 3 ;
    printf ( "\nAddress of i = %u", &i);
    printf ( "\nValue of i = %d", i);
    printf ( "\nValue of i = %d", *(&i));
    }

Output :

Address of i = 65524
Value of i = 3

Explanation :

• The pointer points to the address 65524 of variable i, that contains the value of i i.e 3
• Pointer points to ->65524 address that points to =>value 3
• &i gives the address of the variable i.
• *i gives the value store at the address of i.
• ‘&’ => ‘address of ’ operator.
• The expression &i in the first printf() statement returns the address of the variable i, which in this case happens to be 65524.
• As 65524 is an address, there is no sign associated with it. So to print the address we use ‘%u’ which is a format specifier for printing an unsigned integer.
• The another pointer operator is ‘*’ called ‘value at address’ operator which gives the value stored at a particular address.
• The ‘value at address’ operator is also called ‘indirection’ operator.
• *(&i) is same as printing the value of i.