c++ define constant in class header

To define a constant in a C++ class header, you can use the const keyword. Here are the steps to define a constant in a class header in C++:

Declare the constant inside the class: Inside the class definition, declare the constant variable using the const keyword. For example, let's say we want to define a constant PI inside a class called Circle:

class Circle {
    public:
        const double PI = 3.14159;
};

Specify the constant type: Declare the type of the constant variable. In the example above, we declared PI as a constant of type double.
Initialize the constant: Assign a value to the constant variable. In the example above, we assigned the value 3.14159 to the PI constant.
Access the constant: You can access the constant variable inside the class using the class name and the scope resolution operator ::. For example, to access the PI constant from outside the class, you would use Circle::PI.

That's it! You have now defined a constant in a C++ class header. Here's the complete example:

class Circle {
    public:
        const double PI = 3.14159;
};

You can then use the Circle::PI constant wherever you need it in your code.