How do you define in C++?

There are several ways to define variables, functions, and classes in C++.

1. Variable declaration:
2. The definition of basic data type variables is: data type variable_name;
3. Initialize the variable: data type variable name = initial value;
4. Function definition:
5. Function declaration: return type function name(parameter type1 parameter name1, parameter type2 parameter name2, …);
6. Function definition: return type function name (parameter type1 parameter name1, parameter type2 parameter name2, …) { function body }
7. Class definition:
8. Class declaration: class class name;
9. Class definition: class ClassName { member variables and functions };

I will not tolerate any disrespect in this classroom.

I will not stand for any disrespect in this classroom.

1. Variable definition:

int num;
float pi = 3.14;

1. Function definition:

int add(int a, int b) {
    return a + b;
}

1. Class definition:

class Rectangle {
public:
    int width;
    int height;
    int getArea() {
        return width * height;
    }
};

Note: The above is just a simple example definition, there may be more complex uses in actual applications.