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Pointer Arithmetic in C

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Introduction

Pointer arithmetic allows us to perform operations on pointers.
It is mainly used with arrays and helps in efficient memory access.

👉 Instead of using indexing, we can use pointer arithmetic to access elements.

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What is Pointer Arithmetic?

Pointer arithmetic means:
👉 Performing mathematical operations on pointers

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Allowed Operations

• ✔ Addition (+)
• ✔ Subtraction (-)
• ✔ Increment (++)
• ✔ Decrement (--)

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1. Pointer Increment

#include <stdio.h>

int main() {
    int arr[] = {10, 20, 30};
    int *ptr = arr;

    printf("%d\n", *ptr);
    ptr++;
    printf("%d\n", *ptr);

    return 0;
}

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Output

10
20

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Explanation

👉 ptr++ moves pointer to next element

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2. Pointer Addition

#include <stdio.h>

int main() {
    int arr[] = {5, 10, 15};
    int *ptr = arr;

    printf("%d\n", *(ptr + 2));

    return 0;
}

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Output

15

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3. Pointer Subtraction

#include <stdio.h>

int main() {
    int arr[] = {1, 2, 3, 4};
    int *p1 = &arr[3];
    int *p2 = &arr[1];

    printf("%ld", p1 - p2);

    return 0;
}

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Output

2

👉 Difference between positions

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4. Pointer Decrement

#include <stdio.h>

int main() {
    int arr[] = {10, 20, 30};
    int *ptr = &arr[2];

    printf("%d\n", *ptr);
    ptr--;
    printf("%d\n", *ptr);

    return 0;
}

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Output

30
20

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Pointer Arithmetic Table

Operation	Meaning	Example
ptr++	Next element	Move forward
ptr--	Previous element	Move backward
ptr + n	Move n steps	Jump forward
ptr - n	Move back n steps	Jump backward

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Important Notes

• Pointer moves based on data type size
• int → 4 bytes
• char → 1 byte

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Common Mistakes

• ❌ Accessing invalid memory
• ❌ Wrong pointer type
• ❌ Out-of-bounds access
• ❌ Misunderstanding pointer movement

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Pro Tips

• ✔ Use pointers with arrays
• ✔ Understand memory layout
• ✔ Practice pointer problems
• ✔ Avoid unsafe operations

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Conclusion

Pointer arithmetic is a powerful feature in C. It helps in efficient data access and improves performance.

👉 Master it to write optimized programs.

👉 This article is part of Dharani Tech Edu Hub — where learning programming is made simple and practical.