Introduction to Programming in C

📘 Pointers and Arrays in C

Pointers and arrays are deeply interconnected in the C programming language. Understanding how they work together is crucial for mastering memory management, dynamic data structures, and function argument passing.

🔹 Quick Recap: What is a Pointer?

A pointer is a variable that stores the memory address of another variable.

int x = 10;
int *p = &x;  // p holds the address of x
printf("%d", *p);  // prints the value of x (10)

🔹 Relationship Between Arrays and Pointers

• The name of an array is a pointer to its first element.
• arr[i] is equivalent to *(arr + i)
• Array elements can be accessed using pointer arithmetic.

🔁 Example: Array Access Using Pointers

#include <stdio.h>

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

    for(int i = 0; i < 5; i++) {
        printf("Value: %d, Address: %p\n", *(ptr + i), (ptr + i));
    }
    return 0;
}

📦 Pointer Arithmetic

• ptr + 1 points to the next element
• *(ptr + i) gets the i-th element
• Pointer arithmetic is based on the size of the data type

📘 Using Pointers to Iterate Over Arrays

int marks[4] = {70, 80, 90, 100};
int *p = marks;

while (p < marks + 4) {
    printf("%d\n", *p);
    p++;
}

📚 Real-Life Example (UdaanPath)

Let’s say UdaanPath is storing the marks of students from an online exam, and we want to compute the total using pointers:

#include <stdio.h>

int main() {
    int marks[] = {85, 92, 76, 88, 95};
    int *ptr = marks;
    int total = 0;

    for (int i = 0; i < 5; i++) {
        total += *(ptr + i);
    }

    printf("Total marks on UdaanPath = %d\n", total);
    return 0;
}

📌 Array of Pointers

Useful for handling arrays of strings or dynamic memory.

char *names[] = {"Kuldeep", "Anjali", "Ravi"};

for(int i = 0; i < 3; i++) {
    printf("%s\n", names[i]);
}

📝 Practice Questions

1. Write a program to find the maximum element in an array using pointers.
2. Reverse an array using pointer swapping.
3. Print even elements of an array using pointer logic.
4. Access 2D array elements using a pointer.

✅ Summary

• Pointers and arrays are closely related in C.
• You can iterate over arrays using pointer arithmetic.
• Understanding pointers unlocks deeper C programming techniques.

🚀 Coming Next

In the next chapter, we’ll learn about Dynamic Memory Allocation — how to create memory at runtime using malloc, calloc, and manage it with free.