How can polymorphism be implemented in the C language?

In C language, polymorphism can be implemented using function pointers and structures. The specific steps are as follows:

1. Define a base class structure that includes a function pointer member to point to member functions of different derived classes.

typedef struct {
    void (*func)();
} Base;

1. Define a derived class structure and define specific member functions within it.

typedef struct {
    Base base;
    // 派生类的其他成员
} Derived;

1. Implement member functions of the derived class.

void derived_func() {
    // 派生类的具体实现
}

1. Assign the member functions of the derived class to the function pointers of the base class.

Derived derived;
Base* base = (Base*)&derived;
base->func = derived_func;

1. Invoke polymorphic function.

base->func();

This achieves polymorphism in the C language. During runtime, different derived class implementations are called based on the specific member function pointed to by the function pointer.