C++ Array of Structs

Introduction

An array of structs in C++ allows you to manage and manipulate collections of related data in an organized way. By defining a struct and then creating an array of that struct, you can efficiently handle multiple records, such as student information, employee details, etc.

Defining a Struct and Creating an Array of Structs

To define an array of structs, you first define a struct with the necessary members, and then create an array of that struct type.

Example: Defining a Struct and Creating an Array

#include <iostream>
using namespace std;

struct Student {
    string name;
    int age;
    double grade;
};

int main() {
    // Create an array of Student structs
    Student students[3] = {
        {"Aarav", 20, 88.5},
        {"Siya", 21, 92.0},
        {"Rohan", 19, 75.0}
    };

    // Print student data
    for (int i = 0; i < 3; i++) {
        cout << "Student " << i + 1 << ": " << students[i].name
             << ", Age: " << students[i].age
             << ", Grade: " << students[i].grade << endl;
    }

    return 0;
}

Output

Student 1: Aarav, Age: 20, Grade: 88.5
Student 2: Siya, Age: 21, Grade: 92
Student 3: Rohan, Age: 19, Grade: 75

Explanation

• The Student struct is defined with name, age, and grade members.
• An array of Student structs, students, is created and initialized with data for three students.
• A loop iterates through the array, printing the details of each student.

Practical Examples

Example 1: Calculating the Average Grade

#include <iostream>
using namespace std;

struct Student {
    string name;
    int age;
    double grade;
};

double calculateAverageGrade(Student students[], int size) {
    double total = 0;
    for (int i = 0; i < size; i++) {
        total += students[i].grade;
    }
    return total / size;
}

int main() {
    Student students[3] = {
        {"Aarav", 20, 88.5},
        {"Siya", 21, 92.0},
        {"Rohan", 19, 75.0}
    };

    int size = 3;
    double averageGrade = calculateAverageGrade(students, size);

    cout << "Average Grade: " << averageGrade << endl;

    return 0;
}

Output

Average Grade: 85.1667

Explanation

• The calculateAverageGrade function takes an array of Student structs and the array size as arguments.
• It calculates and returns the average grade of the students.
• The main function initializes the array, calls the calculateAverageGrade function, and prints the average grade.

Example 2: Finding the Youngest Student

#include <iostream>
using namespace std;

struct Student {
    string name;
    int age;
    double grade;
};

int findYoungestStudent(Student students[], int size) {
    int youngestIndex = 0;
    for (int i = 1; i < size; i++) {
        if (students[i].age < students[youngestIndex].age) {
            youngestIndex = i;
        }
    }
    return youngestIndex;
}

int main() {
    Student students[3] = {
        {"Aarav", 20, 88.5},
        {"Siya", 21, 92.0},
        {"Rohan", 19, 75.0}
    };

    int size = 3;
    int youngestIndex = findYoungestStudent(students, size);

    cout << "Youngest Student: " << students[youngestIndex].name
         << ", Age: " << students[youngestIndex].age << endl;

    return 0;
}

Output

Youngest Student: Rohan, Age: 19

Explanation

• The findYoungestStudent function takes an array of Student structs and the array size as arguments.
• It finds and returns the index of the youngest student.
• The main function initializes the array, calls the findYoungestStudent function, and prints the details of the youngest student.

Example 3: Sorting Students by Grade

#include <iostream>
#include <algorithm>
using namespace std;

struct Student {
    string name;
    int age;
    double grade;
};

// Comparator function to sort students by grade
bool compareGrades(Student a, Student b) {
    return a.grade > b.grade; // Sort in descending order
}

int main() {
    Student students[3] = {
        {"Aarav", 20, 88.5},
        {"Siya", 21, 92.0},
        {"Rohan", 19, 75.0}
    };

    int size = 3;

    // Sort the students by grade
    sort(students, students + size, compareGrades);

    // Print sorted student data
    for (int i = 0; i < size; i++) {
        cout << "Student " << i + 1 << ": " << students[i].name
             << ", Age: " << students[i].age
             << ", Grade: " << students[i].grade << endl;
    }

    return 0;
}

Output

Student 1: Siya, Age: 21, Grade: 92
Student 2: Aarav, Age: 20, Grade: 88.5
Student 3: Rohan, Age: 19, Grade: 75

Explanation

• The compareGrades function is a comparator function used to sort students by their grades in descending order.
• The sort function from the <algorithm> header sorts the array of students using the compareGrades function.
• The sorted array is printed, showing students ordered by their grades.

Conclusion

An array of structs in C++ provides a structured way to manage and manipulate collections of related data. This chapter covered the basics of defining a struct and creating an array of that struct type, along with practical examples demonstrating how to calculate the average grade, find the youngest student, and sort students by grade. Understanding how to use arrays of structs effectively is essential for organizing and processing complex data in C++ programs.