🏗️Structure

Collection of different data types

• Basic Definition: A struct is defined using the struct keyword, followed by the struct name and a block containing member variables.

  struct Point {
      int x;
      int y;
  };

• Creating Instances: You can create instances of a struct like this:

  Point p1;
  p1.x = 10;
  p1.y = 20;
  
  // Or using an initializer list (C++11 and later)
  Point p2 = {30, 40};

• Member Access: Access struct members using the dot (.) operator:

  std::cout << "p1: (" << p1.x << ", " << p1.y << ")" << std::endl;

• Functions in Structs: Structs can also contain functions (methods):

  struct Rectangle {
      int width;
      int height;
  
      int area() {
          return width * height;
      }
  };

• Constructors: You can define constructors for initialization:

  struct Person {
      std::string name;
      int age;
  
      Person(std::string n, int a) : name(n), age(a) {}
  };
  
  Person alice("Alice", 30);

• Default Access Specifier: In a struct, members are public by default (unlike in classes where they're private by default).

• Nested Structs: You can nest structs within other structs:

  struct Address {
      std::string street;
      std::string city;
  };
  
  struct Employee {
      std::string name;
      Address workAddress;
  };

• Pointers to Structs: You can create pointers to structs and access members using the arrow (->) operator:

  Point* pPtr = &p1;
  std::cout << pPtr->x << ", " << pPtr->y << std::endl;

• Struct vs Class: The main difference is the default access specifier. Structs are often used for simple data structures, while classes are used for more complex objects with behaviors.

• Memory Alignment: Structs can have padding between members for memory alignment. You can use #pragma pack or __attribute__((packed)) to control this.

Example:

#include <iostream>
#include <string>

struct Date {
    int day;
    int month;
    int year;

    Date(int d, int m, int y) : day(d), month(m), year(y) {}

    void display() {
        std::cout << day << "/" << month << "/" << year << std::endl;
    }
};

struct Person {
    std::string name;
    Date birthDate;

    Person(std::string n, Date bd) : name(n), birthDate(bd) {}

    void introduce() {
        std::cout << "Hi, I'm " << name << ". I was born on ";
        birthDate.display();
    }
};

int main() {
    Date bobBirthDate(15, 6, 1990);
    Person bob("Bob", bobBirthDate);

    bob.introduce();

    return 0;
}

Run it here.