C Pointers

1. What is a Pointer?

A pointer is a variable that stores the memory address of another variable.
Instead of holding a value directly, it holds where the value is stored.

Syntax:

data_type → type of the variable the pointer points to
* → indicates the variable is a pointer

2. Declaring and Using Pointers

#include <stdio.h>

int main() {
int num = 50; // normal variable
int *ptr = &num; // pointer storing address of num

printf("Value of num: %d\n", num);
printf("Address of num: %p\n", &num);
printf("Value stored in ptr (address): %p\n", ptr);
printf("Value pointed by ptr: %d\n", *ptr); // dereferencing

return 0;
}

#include <stdio.h>

int main() {

int num = 50; // normal variable

int *ptr = &num; // pointer storing address of num

printf("Value of num: %d\n", num);

printf("Address of num: %p\n", &num);

printf("Value stored in ptr (address): %p\n", ptr);

printf("Value pointed by ptr: %d\n", *ptr); // dereferencing

return 0;

}

Output (example):

*ptr is used to access the value stored at the address (dereferencing).

3. Changing Value Using Pointers

Output:

Using pointers, you can modify the variable directly via its address.

4. Pointer and Arrays

The name of an array is treated as a pointer to its first element.

#include <stdio.h>

int main() {
int numbers[5] = {10, 20, 30, 40, 50};
int *ptr = numbers; // points to numbers[0]

for (int i = 0; i < 5; i++) {
printf("Element %d = %d\n", i, *(ptr + i)); // pointer arithmetic
}

return 0;
}

#include <stdio.h>

int main() {

int numbers[5] = {10, 20, 30, 40, 50};

int *ptr = numbers; // points to numbers[0]

for (int i = 0; i < 5; i++) {

printf("Element %d = %d\n", i, *(ptr + i)); // pointer arithmetic

}

return 0;

}

Output:

5. Pointer to Pointer

A pointer can store the address of another pointer.

Output:

6. Pointers and Functions (Call by Reference)

Output:

Pointers allow functions to modify variables outside their scope.

7. Key Points About Pointers

Declaration: data_type *ptr;
Address-of operator &: stores the memory address in pointer.
Dereference *: access or modify the value at the pointer.
Arrays and pointers are closely related.
Pointers are essential for:
- Dynamic memory allocation
- Passing arguments by reference
- Linked lists, trees, and other data structures

C Pointers

1. What is a Pointer?

2. Declaring and Using Pointers

3. Changing Value Using Pointers

4. Pointer and Arrays

5. Pointer to Pointer

6. Pointers and Functions (Call by Reference)

7. Key Points About Pointers

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C Pointers

1. What is a Pointer?

2. Declaring and Using Pointers

3. Changing Value Using Pointers

4. Pointer and Arrays

5. Pointer to Pointer

6. Pointers and Functions (Call by Reference)

7. Key Points About Pointers

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