In what scenarios is it better to use a struct vs a class in C++?

 

In C++, both struct and class are used to define user-defined data types, but they have some differences in terms of default access specifiers and intended use cases. Here are some scenarios where using a struct might be more suitable than using a class:

1. Simple Data Container:
   • Use struct when you need a simple data container with little to no functionality, primarily holding data members that don't require complex methods or encapsulation.
   • Use class when you need to encapsulate data and provide methods for manipulating or interacting with that data.

Example:

cpp

// Using struct for a simple data container
struct Point {
    int x;
    int y;
};

// Using class for encapsulation and methods
class Circle {
private:
    double radius;

public:
    Circle(double r) : radius(r) {}

    double getArea() {
        return 3.14159 * radius * radius;
    }
};

2. Default Access Specifiers:
   • Members in a struct have public access by default.
   • Members in a class have private access by default.

Example:

cpp

struct MyStruct {
    int x;  // Public by default
};

class MyClass {
    int y;  // Private by default
};

3. Backward Compatibility:
   • In older versions of C++, struct was commonly used for data-only structures, while class was used for more complex types with methods.
   • If you want to maintain backward compatibility with code that assumes struct implies a simple data structure, using struct might be preferred.

Example:

cpp

// Using struct for backward compatibility
struct LegacyStruct {
    int data;
    void processData() {
        // ...
    }
};

4. Interoperability:
   • If you're working with C libraries or external APIs that use plain struct definitions, it might be more convenient to use struct in your C++ code.

Example:

cpp

// Interoperability with C library
extern "C" {
    struct CStruct {
        int value;
    };
}

It's important to note that modern C++ practices promote using class by default for encapsulation and information hiding. The distinctions between struct and class have become less pronounced over time due to language evolution. Choose between struct and class based on your design requirements, readability, and consistency with existing code if applicable.