**Course Title:** Mastering C: From Fundamentals to Advanced Programming **Section Title:** Structures and Unions **Topic:** Create a program that uses structures and unions to model real-world data.(Lab topic) **Introduction:** In this lab topic, we will explore how to use structures and unions to model real-world data in C programming. By the end of this topic, you will have a better understanding of how to effectively use structures and unions to represent complex data and how to manipulate this data in your C programs. **Modeling Real-World Data with Structures:** Structures in C programming are used to group together related variables under a single unit. This allows us to model complex data in a more organized and efficient way. Let's consider an example of modeling student records using a structure. ```c #include <stdio.h> // Define a structure to represent student records typedef struct { int rollNumber; char name[50]; float marks; } Student; int main() { // Declare an array of students Student students[3]; // Initialize the student records for (int i = 0; i < 3; i++) { printf("Enter roll number: "); scanf("%d", &students[i].rollNumber); printf("Enter name: "); scanf("%s", students[i].name); printf("Enter marks: "); scanf("%f", &students[i].marks); } // Display the student records for (int i = 0; i < 3; i++) { printf("Roll Number: %d\n", students[i].rollNumber); printf("Name: %s\n", students[i].name); printf("Marks: %.2f\n\n", students[i].marks); } return 0; } ``` In this example, we define a `Student` structure to represent student records, which contains `rollNumber`, `name`, and `marks` fields. We then declare an array of `Student` structures to store multiple student records. **Modeling Real-World Data with Unions:** Unions in C programming are used to store different types of data in the same memory location. Let's consider an example of modeling employee records using a union. ```c #include <stdio.h> // Define a union to represent employee records typedef union { int employeeId; float salary; } Employee; int main() { // Declare an employee Employee employee; // Set the employee ID employee.employeeId = 123; printf("Employee ID: %d\n", employee.employeeId); // Set the salary employee.salary = 5000.0; printf("Salary: %.2f\n", employee.salary); return 0; } ``` In this example, we define an `Employee` union to represent employee records, which contains `employeeId` and `salary` fields. We then declare an `Employee` union to store an employee record. Note that the union can store only one type of data at a time. **Combining Structures and Unions:** We can combine structures and unions to model complex data in C programming. Let's consider an example of modeling bank account records using a structure and a union. ```c #include <stdio.h> // Define a union to represent account balance typedef union { int accountNumber; float balance; } Balance; // Define a structure to represent bank account records typedef struct { Balance balance; char accountHolder[50]; } BankAccount; int main() { // Declare a bank account BankAccount account; // Set the account number account.balance.accountNumber = 456; printf("Account Number: %d\n", account.balance.accountNumber); // Set the account holder printf("Enter account holder: "); scanf("%s", account.accountHolder); // Set the balance account.balance.balance = 1000.0; printf("Balance: %.2f\n", account.balance.balance); return 0; } ``` In this example, we define a `Balance` union to represent the account balance, which contains `accountNumber` and `balance` fields. We then define a `BankAccount` structure to represent bank account records, which contains `balance` and `accountHolder` fields. We then declare a `BankAccount` structure to store a bank account record. **Conclusion:** In this lab topic, we have explored how to use structures and unions to model real-world data in C programming. We have seen how to define and use structures and unions to represent complex data and how to manipulate this data in our C programs. By combining structures and unions, we can model complex data in a more organized and efficient way. **Practice Exercises:** 1. Define a structure to represent a point in 3D space, and use it to calculate the distance between two points. 2. Define a union to represent a date in mm/dd/yyyy format, and use it to display the current date. 3. Define a structure to represent a rectangle, and use it to calculate the area and perimeter of the rectangle. **What's Next:** In the next topic, we will explore file I/O in C programming. We will learn how to read and write data from files, and how to work with different types of files. **Leave a Comment or Ask for Help:** If you have any questions or need help with the exercises, please leave a comment below.