Pointer Arithmetic

Introduction

Pointer arithmetic moves pointers by sizeof(type) — p+1 points to the next element in an array.

Understanding the topic

Increment p++ moves to next int element.

Difference p2 - p1 gives element count between pointers.

Bounds Only valid within same array object.

• Increment — p++ moves to next int element.
• Difference — p2 - p1 gives element count between pointers.
• Bounds — Only valid within same array object.

Step-by-step explanation

1. Increment — p++ moves to next int element.
2. Difference — p2 - p1 gives element count between pointers.
3. Bounds — Only valid within same array object.

Informative example

Example program:

#include <stdio.h>

int main(void) {
    int arr[] = {10, 20, 30};
    int *p = arr;
    printf("%d %d\n", *p, *(p + 2));
    return 0;
}

10 30

Execution workflow

Best practices

• Enable warnings: gcc -Wall -Wextra -std=c11 source.c -o app
• Give every variable a defined value before it is read.
• Stay inside array bounds — C will not stop you from over-running a buffer.

Common mistakes

• Reading uninitialized storage — behavior is undefined.
• Dismissing compiler warnings instead of fixing root causes.
• Ignoring NULL returns from malloc, fopen, and similar APIs.

Hands-on exercise

Practice problems:

• Traverse array with pointer only
• Print string with char*

Summary

Pointer Arithmetic in C — Moving by element size within an array object.