DEREFERENCING OF POINTERS

Dereferencing a pointer means accessing the value stored at the memory address that the pointer is pointing to. In C, the * (asterisk) operator is used for dereferencing a pointer.

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Upon dereferencing a pointer, the operation retrieves and returns the value stored in the variable to which the pointer points.

Why do we dereference pointers?

1. It allows access to and manipulation of the data stored at the memory location pointed to by the pointer.
2. Any operation applied to the dereferenced pointer directly affects the value of the variable it points to.

To illustrate the process of dereferencing a pointer, consider the following steps:

• Declare an integer variable ‘point’ to which the pointer will point.

int point= 9;

• Declare an integer pointer variable ‘ptr’.

int *ptr;

• Assign the address of variable ‘point’ to the pointer variable ‘ptr’.

ptr = &point;

• Change the value of variable ‘point’ by dereferencing the pointer ‘ptr’.

*ptr = 8;

The above line modifies the value of variable ‘point’ from 9 to 8 because ‘ptr’ points to the location of ‘point,’ and dereferencing ‘ptr’ (i.e., *ptr = 8) updates the value of ‘point.’

Combining all the steps into a program:

#include <stdio.h>

int main() {
    int point = 9;  // Declare an integer variable 'point'.
    int *ptr;       // Declare an integer pointer variable 'ptr'.
    ptr = &point;   // Assign the address of variable 'point' to the pointer variable 'ptr'.
    *ptr = 8;       // Change the value of variable 'point' by dereferencing the pointer 'ptr'.
    
    printf("The value of point is: %d", point);  // Print the updated value of 'point'.
    
    return 0;
}

Output

The value of point is: 8

Let take another example

#include <stdio.h>

int main() {
    int Digit = 43;         // Declaration of an integer variable 'Digit'.
    int* ptr = &Digit;      // Declaration of an integer pointer 'ptr' pointing to the address of 'Digit*'.

    // Output the memory address of 'Digit' using the pointer (e.g., 0x7ffe5367e044).
    printf("Memory address of Digit: %p\n", ptr);

    // Dereference the pointer to output the value of 'Digit' (e.g., 43).
    printf("Value of Digit: %d\n", *ptr);

    return 0;
}

Output

Memory address of Digit: 0x7ffe5367e044
Value of Digit: 43