Arrays and Pointers in C

Arrays and pointers are tightly connected in C.

If you truly understand this lesson, you will understand how C works internally.

Many students fear pointers only because they do not understand how arrays and pointers relate to each other.

Let us clear that confusion step by step.

Important Truth

In C:

The name of an array behaves like a pointer to its first element.

This does not mean arrays are pointers, but they can be used like pointers in many situations.

Array Memory Layout

Consider this array:

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

In memory, elements are stored in continuous locations:

• arr[0] → first memory block
• arr[1] → next memory block
• and so on…

The array name arr holds the address of the first element.

Array Name as Pointer

These two expressions point to the same memory location:

arr
&arr[0]

That is why this works:

printf("%d", *arr);

It prints the first element of the array.

Accessing Array Elements Using Pointers

Let us access all elements using pointer arithmetic.

#include <stdio.h>

int main() {
    int arr[5] = {10, 20, 30, 40, 50};
    int i;

    for (i = 0; i < 5; i++) {
        printf("%d ", *(arr + i));
    }

    return 0;
}

Explanation:

• arr → points to first element
• arr + i → moves to ith element
• *(arr + i) → value at that location

Using Pointer Variable with Array

We can also use a pointer variable.

int arr[3] = {5, 10, 15};
int *ptr = arr;

printf("%d\n", *ptr);      // 5
printf("%d\n", *(ptr+1));  // 10
printf("%d\n", *(ptr+2));  // 15

Both approaches are valid and commonly used.

Important Difference: Array vs Pointer

Even though arrays act like pointers, they are NOT the same.

• Array size is fixed
• Array name cannot be reassigned
• Pointer can be reassigned

Example (invalid):

arr = ptr;   // ❌ Not allowed

Why This Matters

Understanding arrays and pointers is essential for:

• Dynamic memory allocation
• Function arguments
• Strings
• Data structures

Almost everything advanced in C builds on this concept.

Common Mistakes

• Accessing memory outside array bounds
• Confusing arr and &arr
• Forgetting pointer arithmetic rules

Mini Practice

• Print array elements using pointer only
• Print addresses of each element
• Modify array values using pointer

Quick Quiz

Q1. What does the array name represent?

It represents the address of the first element.

Q2. What is *(arr + i)?

It accesses the ith element of the array.

Q3. Can array names be reassigned?

No, array names cannot be reassigned.

Q4. Why are arrays stored contiguously?

For efficient access using pointer arithmetic.

Q5. Why is this concept important?

It is the foundation for memory handling and data structures.