Object-oriented thinking in C language (implementing inheritance and polymorphism)

Because C language is a process-oriented language, in the process of larger projects, the structure will appear somewhat loose. Management cannot help but be powerless.

In fact, in the process of using C language to write programs, you can also introduce some objects of the image of the idea. Here we will talk about how to express these thoughts in C language:

1. Package

This is the simplest, C language, although there is no class, but there are struct. It's a good thing. We can simulate class behavior by depositing data and function pointers in a struct.

typedef struct _parent{
    int A;
    int b;
    void (*print) (struct _parent *this);
} Parent;

2. Inheritance

It can be a bit difficult to inherit completely in the C language. But if it's simply done, make sure that the subclass contains all the members of the parent class. It's still not difficult.

typedef struct _child{
    parent parent;
    int c;
} child;

3. Polymorphism

This feature is probably the most useful in object-oriented thinking.

It takes a little bit of skill to implement this feature in C, but it's not impossible.

We use the two structural bodies defined above as parent, child. A simple description of a polymorphic example.

void Print_parent (parent *this) {printf ("a =%d. B =%d.\n", This->a, this->b);
    void Print_child (Parent *this) {Child *p = [Child *] this;
printf ("a =%d. B =%d. C =%d.\n", P->parent.a, p->parent.b, p->c);

    Parent *create_parent (int a, int b) {parent *this;
    this = NULL;
    This = (parent *) malloc (sizeof (parent));
        if (this!= NULL) {this->a = A;
        This->b = b;
        This->print = print_parent;
    printf ("Create parent successfully!\n");
return to this;
        } void Destroy_parent (parent **p) {if (*p!= NULL) {free (*p);
        *p = NULL;
    printf ("Delete parent successfully!\n");

    } *create_child (int a, int b, int c) {child *this;
    this = NULL;
    this = (Child *) malloc (sizeof);
        if (this!= NULL) {this->parent.a = A;
        this->parent.b = b;
        This->c = C;
This->parent.print = Print_child;        printf ("Create child successfully!\n");
return to this;
        } void Destroy_child (child **p) {if (*p!= NULL) {free (*p);
        *p = NULL;
    printf ("Delete child successfully!\n");
    int main () {Child *p = Create_child (1, 2, 3);

    Parent *q;
    /*use parent Pointer to point to child*/q = (parent *) p;

    /*be attention!*//*actually The child ' s print function is called!*/q->print (q);
    Destroy_child (&P);

return 0; }