Introduction to Programming in C

📘 Passing Arrays, Structures, and Pointers to Functions

In C, functions provide modularity and reusability. Complex data such as arrays, structures, and pointers can be passed to functions to process them efficiently. This is crucial for writing clean and scalable programs.

🔹 Passing Arrays to Functions

Arrays are always passed by reference (i.e., the base address is passed).

void printArray(int arr[], int size) {
    for(int i = 0; i < size; i++) {
        printf("%d ", arr[i]);
    }
}

int main() {
    int nums[] = {10, 20, 30};
    printArray(nums, 3);
    return 0;
}

📚 UdaanPath Example: Total Score of Students

void totalScore(int scores[], int n) {
    int total = 0;
    for(int i = 0; i < n; i++) {
        total += scores[i];
    }
    printf("Total UdaanPath Score: %d", total);
}

🔹 Passing Multidimensional Arrays

You must specify the column size in the parameter list:

void displayMarks(int marks[][3], int rows) {
    for(int i = 0; i < rows; i++) {
        for(int j = 0; j < 3; j++) {
            printf("%d ", marks[i][j]);
        }
        printf("\n");
    }
}

🔹 Passing Structures to Functions

Structures can be passed either by value or by reference (using pointers).

🧪 By Value

struct Student {
    char name[30];
    int age;
};

void display(struct Student s) {
    printf("Name: %s, Age: %d\n", s.name, s.age);
}

🔁 By Reference

void update(struct Student *s) {
    s->age += 1;
}

📌 Complete UdaanPath Example

#include <stdio.h>
#include <string.h>

struct Course {
    char title[50];
    int duration;
};

void display(struct Course c) {
    printf("Course: %s, Duration: %d hrs\n", c.title, c.duration);
}

void extend(struct Course *c, int extraHours) {
    c->duration += extraHours;
}

int main() {
    struct Course course1 = {"UdaanPath: Learn C Fast", 40};
    display(course1);
    extend(&course1, 5);
    printf("After Extension:\n");
    display(course1);
    return 0;
}

🔹 Passing Pointers to Functions

Allows modification of actual variable values using their addresses.

void swap(int *a, int *b) {
    int temp = *a;
    *a = *b;
    *b = temp;
}

📝 Practice Questions

1. Pass a 1D array to a function and calculate average.
2. Pass a structure of employee to a function and print details.
3. Write a swap() function using pointers.
4. Modify structure data inside a function using pointer.

✅ Summary

• Arrays are passed by reference; structures can be passed both ways.
• Passing pointers allows direct modification of values.
• Use const with pointer parameters if you don’t want the data to be modified.

🚀 Coming Next

In the next chapter, we will explore Enumerations and Typedef — powerful tools for naming constants and simplifying data types.