C++ Structures (struct)

In C++, a structure (or struct) allows multiple related variables to be grouped together under one name. This makes organizing and managing complex data more efficient than using individual variables.

Defining a Structure

Unlike arrays, structures can store multiple data types, including int, string, and bool.

Example: Declaring a Structure

struct {  
    int engineSize;  // Integer member  
    string bikeModel;  // String member  
} motorcycle;  // Structure variable

C++
​x
 
struct {      int engineSize;  // Integer member      string bikeModel;  // String member  } motorcycle;  // Structure variable​

This structure groups an engine size (int) and a model name (string) under motorcycle.

Assigning and Accessing Structure Members

Use the dot (.) operator to assign values and access structure members.

Example: Assigning and Printing Structure Members

#include <iostream>
using namespace std;

int main() {
    struct {  
        int engineSize;  
        string bikeModel;  
    } motorcycle;  

    // Assign values to structure members  
    motorcycle.engineSize = 1000;  
    motorcycle.bikeModel = "ZX-10R";  

    // Print structure members  
    cout << motorcycle.engineSize << "cc\n";  
    cout << motorcycle.bikeModel << "\n";  

    return 0;
}

C++
 
#include <iostream>using namespace std;​int main() {    struct {          int engineSize;          string bikeModel;      } motorcycle;  ​    // Assign values to structure members      motorcycle.engineSize = 1000;      motorcycle.bikeModel = "ZX-10R";  ​    // Print structure members      cout << motorcycle.engineSize << "cc\n";      cout << motorcycle.bikeModel << "\n";  ​    return 0;}​

Output:

1000cc  
ZX-10R

C++
 
1000cc  ZX-10R  ​

Using One Structure for Multiple Variables

To create multiple instances of the same structure, separate structure variables with commas (,).

Example: Two Motorcycles Using One Structure

#include <iostream>
using namespace std;

int main() {
    struct {  
        string brand;  
        string model;  
        int year;  
    } bike1, bike2;  

    // Assign values to the first bike  
    bike1.brand = "Ducati";  
    bike1.model = "Panigale V4";  
    bike1.year = 2022;  

    // Assign values to the second bike  
    bike2.brand = "Yamaha";  
    bike2.model = "R1";  
    bike2.year = 2021;  

    // Print details  
    cout << bike1.brand << " " << bike1.model << " " << bike1.year << "\n";  
    cout << bike2.brand << " " << bike2.model << " " << bike2.year << "\n";  

    return 0;
}

C++
 
#include <iostream>using namespace std;​int main() {    struct {          string brand;          string model;          int year;      } bike1, bike2;  ​    // Assign values to the first bike      bike1.brand = "Ducati";      bike1.model = "Panigale V4";      bike1.year = 2022;  ​    // Assign values to the second bike      bike2.brand = "Yamaha";      bike2.model = "R1";      bike2.year = 2021;  ​    // Print details      cout << bike1.brand << " " << bike1.model << " " << bike1.year << "\n";      cout << bike2.brand << " " << bike2.model << " " << bike2.year << "\n";  ​    return 0;}​

Output:

Ducati Panigale V4 2022  
Yamaha R1 2021

C++
 
Ducati Panigale V4 2022  Yamaha R1 2021  ​

Named Structures

To make a structure reusable anywhere, give it a name after the struct keyword.

Example: Creating a Named Structure

struct Motorcycle {  
    string brand;  
    string model;  
    int year;  
};

C++
 
struct Motorcycle {      string brand;      string model;      int year;  };​

To declare a variable using this structure:

Motorcycle myBike;

C++
 
Motorcycle myBike;​

Example: Using a Named Structure

#include <iostream>
using namespace std;

// Declare a named structure
struct Motorcycle {  
    string brand;  
    string model;  
    int year;  
};

int main() {
    // Create motorcycle instances
    Motorcycle bike1;  
    bike1.brand = "Honda";  
    bike1.model = "CB1000R";  
    bike1.year = 2020;  

    Motorcycle bike2;  
    bike2.brand = "Kawasaki";  
    bike2.model = "Z900";  
    bike2.year = 2021;  

    // Print structure members  
    cout << bike1.brand << " " << bike1.model << " " << bike1.year << "\n";  
    cout << bike2.brand << " " << bike2.model << " " << bike2.year << "\n";  

    return 0;
}

C++
 
#include <iostream>using namespace std;​// Declare a named structurestruct Motorcycle {      string brand;      string model;      int year;  };​int main() {    // Create motorcycle instances    Motorcycle bike1;      bike1.brand = "Honda";      bike1.model = "CB1000R";      bike1.year = 2020;  ​    Motorcycle bike2;      bike2.brand = "Kawasaki";      bike2.model = "Z900";      bike2.year = 2021;  ​    // Print structure members      cout << bike1.brand << " " << bike1.model << " " << bike1.year << "\n";      cout << bike2.brand << " " << bike2.model << " " << bike2.year << "\n";  ​    return 0;}​