Data Structures and Algorithms in C (DSA)

📘 Structures and Unions with Arrays

C language offers composite data types called structures and unions that allow grouping of different types of data under one name. These are especially useful when managing records like student profiles, product data, etc.

🏗️ What is a Structure?

A structure (struct) is a user-defined data type that groups variables of different data types under one name.

struct Student {
    int roll;
    char name[50];
    float marks;
};
  

📦 Declaring & Accessing Structure Variables

struct Student s1;
strcpy(s1.name, "Amit");
s1.roll = 101;
s1.marks = 87.5;
printf("Name: %s, Roll: %d, Marks: %.2f", s1.name, s1.roll, s1.marks);
  

🧑‍🎓 Array of Structures – Example (UdaanPath)

Suppose you're storing student data for a scholarship test on UdaanPath:

struct Student students[3];

for (int i = 0; i < 3; i++) {
    printf("Enter name, roll and marks for student %d: ", i+1);
    scanf("%s %d %f", students[i].name, &students[i].roll, &students[i].marks);
}
  

🔄 Passing Structure to Functions

void printStudent(struct Student s) {
    printf("Name: %s | Roll: %d | Marks: %.2f\n", s.name, s.roll, s.marks);
}
  

⚖️ Structure vs Union

🔗 Union Example

union Data {
    int i;
    float f;
    char str[20];
};

union Data d;
d.i = 10;
printf("d.i = %d", d.i);
  

📚 Practice Tasks

• Create an array of 5 employees with id, name, salary
• Write a function to print student details using structures
• Use union to store different sensor types (int, float, char)
• Compare memory size of structure and union with sizeof()

✅ Summary

• Structures group different data types in one unit
• Unions share memory and are space efficient
• Both are key for real-world modeling like records, packets, events

📤 Coming Next

In the next chapter, we’ll learn how to pass arrays, structures, and pointers to functions — enabling modular and efficient code structure.