C++ Structures

What is a struct?

A struct is like a class but with public as the default access specifier. Structs are ideal for plain data containers without complex behavior.

#include <iostream>
using namespace std;

struct Point {
    double x;
    double y;

    double distanceTo(const Point& other) {
        double dx = x - other.x;
        double dy = y - other.y;
        return sqrt(dx*dx + dy*dy);
    }
};

int main() {
    Point p1 = {0.0, 0.0};
    Point p2 = {3.0, 4.0};
    cout << "Distance: " << p1.distanceTo(p2) << endl;   // 5
    return 0;
}

Output:

Distance: 5

struct vs class

Array of Structs

struct Student {
    string name;
    int    score;
};

Student students[3] = {
    {"Alice", 95},
    {"Bob",   82},
    {"Carol", 78}
};

for (const Student& s : students) {
    cout << s.name << ": " << s.score << endl;
}

#include <iostream>
using namespace std;

struct Book {
    string title, author;
    int year;
    double price;
};

int main() {
    Book books[] = {
        {"C++ Primer", "Lippman", 2012, 49.99},
        {"Effective C++", "Meyers", 2005, 39.99},
        {"The C++ Programming Language", "Stroustrup", 2013, 55.00}
    };
    Book& mostExpensive = books[0];
    for (Book& b : books)
        if (b.price > mostExpensive.price) mostExpensive = b;
    cout << "Most expensive: " << mostExpensive.title << endl;
    return 0;
}

Summary

• Structs group related data; members are public by default.
• Structs can have constructors and methods like classes.
• Use structs for simple data bundles; classes for complex OOP.