C++ is a high-level programming language that has a lot of features to offer. It is used to build operating systems, browsers, game engines, and much more. As a C++ programmer, you need to know the essential elements that make up the language. In this guide, we will explore the must-have class, struct, and union and explain why they are important.
What is a Class in C++?
A class is a user-defined data type that contains data members and member functions. It is a blueprint for creating objects. The data members can be of any data type, including primitive types like int and float, or user-defined types like struct and class. The member functions are the operations that can be performed on the data members.
Here is an example of a class in C++:
class Rectangle {
public:
int length;
int breadth;
int area() {
return length * breadth;
}
};
In this example, we have defined a class called Rectangle. It has two data members, length, and breadth, and one member function, area, which returns the area of the rectangle.
What is a Struct in C++?
A struct is another user-defined data type in C++. It is similar to a class but with some differences. Like a class, it can have data members and member functions. However, in a struct, the default access specifier is public, whereas in a class, it is private. Also, a struct cannot have inheritance, whereas a class can.
Here is an example of a struct in C++:
struct Point {
int x;
int y;
void print() {
cout << "x = " << x << ", y = " << y << endl;
}
};
In this example, we have defined a struct called Point. It has two data members, x and y, and one member function, print, which prints the values of x and y.
What is a Union in C++?
A union is a user-defined data type that allows you to store different types of data in the same memory location. It is similar to a struct in that it can have data members, but unlike a struct, all the data members share the same memory location. This means that only one data member can be accessed at a time.
Here is an example of a union in C++:
union Data {
int i;
float f;
char c;
};
In this example, we have defined a union called Data. It has three data members, i, f, and c. When you create an object of this union, you can only access one data member at a time. For example:
Data d;
d.i = 10;
cout << d.i << endl; // Output: 10
d.f = 3.14;
cout << d.f << endl; // Output: 3.14
d.c = 'A';
cout << d.c << endl; // Output: A
cout << d.i << endl; // Output: 65
In this example, we first set the value of i to 10 and then print it. Next, we set the value of f to 3.14 and print it. Finally, we set the value of c to 'A' and print it. When we print the value of i again, we get 65 because 'A' has an ASCII value of 65.
Conclusion
In this guide, we have explored the essential elements of C++ programming: class, struct, and union. We have explained what they are and why they are important. As a C++ programmer, it is essential to have a good understanding of these concepts to be able to write efficient and effective code.
FAQ
What is the difference between a class and a struct in C++?
The main difference between a class and a struct in C++ is the default access specifier. In a class, it is private, whereas in a struct, it is public. Also, a class can have inheritance, whereas a struct cannot.
Can a struct have member functions in C++?
Yes, a struct can have member functions in C++. It is similar to a class in this regard.
What is an access specifier in C++?
An access specifier in C++ is a keyword that defines the visibility of data members and member functions. There are three access specifiers in C++: public, private, and protected.
What is the difference between a union and a struct in C++?
The main difference between a union and a struct in C++ is that a union allows you to store different types of data in the same memory location, whereas a struct does not. In a struct, each data member has its own memory location.
Can a union have member functions in C++?
No, a union cannot have member functions in C++.