1. Pointers & References

Introduction to Pointers

A pointer is a variable that stores the Memory Address of another variable instead of holding traditional values.

Assignment of Address

The Address-of Operator (&) is used to get the physical memory address of an initialized variable.

int a = 10;
int *p = &a; // p points to 'a'

Indirection / Dereferencing Operator (*)

The Asterisk operator retrieves or alters the value exactly at a particular memory address.

int value = *p; // Reads whatever 'p' holds

Modifying Values Explicitly Using Pointers

*p = 50; // Directly replaces the value in variable 'a'

Difference between Ordinary Variables and Pointers

Field	Ordinary Variable	Pointer Variable
Data Bound	Stores mathematical, raw alphanumeric values.	Stores Hexadecimal physical RAM locations.
Logic	Read immediately directly.	Requires indirection/dereferencing.
Math Scope	General mathematical algebra.	Pointer algorithmic math.

Pointers & Arrays

The core connection between arrays and pointers is that the specific name of an array inherently automatically acts as a constant pointer holding the exact base address.

int arr[5] = {10, 20, 30, 40, 50};
// 'arr' evaluates implicitly to '&arr[0]'

Accessing generic elements via implicit pointer bindings:

• arr[i] is fully equivalent internally to *(arr + i)
• &arr[i] is essentially functionally exactly (arr + i)

Function Pointers

A pointer doesn't strictly have to point only to variables; it can point physically to structurally compiled functions.

void hello() { printf("Hello"); }

int main() {
    // Declarative initialization of function pointer
    void (*p)() = hello; 
    
    // Explicit dynamic execution natively
    p(); 
    return 0;
}

Null Pointer

A pointer that evaluates to nothing and points nowhere explicitly:

int *p = NULL; // Safe initialization technique.

Pointer to Pointer (Double Pointer)

A distinct pointer seamlessly storing the physical address of another pointer variable.

Syntax utilizing a Double Asterisk (**):

int x = 10;
int *p = &x;     // Pointer targeting Integer
int **ptr2 = &p; // Pointer explicitly targeting another Pointer

To alter the root integer structure, you execute **ptr2 = 20;.