用C编写面向对象代码有哪些方法?特别是在多态性方面。


另请参阅此堆栈溢出问题C中的面向对象。


当前回答

在Jim Larson 1996年在312节编程午餐研讨会上的演讲中有一个使用C进行继承的例子:高级和低级C。

其他回答

是的。事实上,Axel Schreiner免费提供了他的书《ANSI-C中的面向对象编程》,这本书相当全面地涵盖了这个主题。

哪些文章或书籍适合在C语言中使用面向对象的概念?

Dave Hanson的《C接口与实现》在封装和命名方面非常出色,在函数指针的使用方面也非常出色。Dave没有尝试模拟继承。

关于c语言OOP的另一个变化,请参阅http://slkpg.byethost7.com/instance.html。它强调仅使用本机c实现实例数据的可重入性,多重继承使用函数包装器手动完成。保持型号安全。下面是一个小例子:

typedef struct _peeker
{
    log_t     *log;
    symbols_t *sym;
    scanner_t  scan;            // inherited instance
    peek_t     pk;
    int        trace;

    void    (*push) ( SELF *d, symbol_t *symbol );
    short   (*peek) ( SELF *d, int level );
    short   (*get)  ( SELF *d );
    int     (*get_line_number) ( SELF *d );

} peeker_t, SlkToken;

#define push(self,a)            (*self).push(self, a)
#define peek(self,a)            (*self).peek(self, a)
#define get(self)               (*self).get(self)
#define get_line_number(self)   (*self).get_line_number(self)

INSTANCE_METHOD
int
(get_line_number) ( peeker_t *d )
{
    return  d->scan.line_number;
}

PUBLIC
void
InitializePeeker ( peeker_t  *peeker,
                   int        trace,
                   symbols_t *symbols,
                   log_t     *log,
                   list_t    *list )
{
    InitializeScanner ( &peeker->scan, trace, symbols, log, list );
    peeker->log = log;
    peeker->sym = symbols;
    peeker->pk.current = peeker->pk.buffer;
    peeker->pk.count = 0;
    peeker->trace = trace;

    peeker->get_line_number = get_line_number;
    peeker->push = push;
    peeker->get = get;
    peeker->peek = peek;
}

是的,这是可能的。

这是纯C语言,没有宏预处理。它具有继承、多态、数据封装(包括私有数据)。它没有等效的受保护限定符,这意味着私有数据在整个继承链中也是私有的。

#include "triangle.h"
#include "rectangle.h"
#include "polygon.h"

#include <stdio.h>

int main()
{
    Triangle tr1= CTriangle->new();
    Rectangle rc1= CRectangle->new();

    tr1->width= rc1->width= 3.2;
    tr1->height= rc1->height= 4.1;

    CPolygon->printArea((Polygon)tr1);

    printf("\n");

    CPolygon->printArea((Polygon)rc1);
}

/*output:
6.56
13.12
*/

命名空间通常通过以下方式实现:

stack_push(thing *)

而不是

stack::push(thing *)

要将C结构体变成类似c++类的东西,您可以转向:

class stack {
     public:
        stack();
        void push(thing *);
        thing * pop();
        static int this_is_here_as_an_example_only;
     private:
        ...
};

Into

struct stack {
     struct stack_type * my_type;
     // Put the stuff that you put after private: here
};
struct stack_type {
     void (* construct)(struct stack * this); // This takes uninitialized memory
     struct stack * (* operator_new)(); // This allocates a new struct, passes it to construct, and then returns it
     void (*push)(struct stack * this, thing * t); // Pushing t onto this stack
     thing * (*pop)(struct stack * this); // Pops the top thing off the stack and returns it
     int this_is_here_as_an_example_only;
}Stack = {
    .construct = stack_construct,
    .operator_new = stack_operator_new,
    .push = stack_push,
    .pop = stack_pop
};
// All of these functions are assumed to be defined somewhere else

和做的事:

struct stack * st = Stack.operator_new(); // Make a new stack
if (!st) {
   // Do something about it
} else {
   // You can use the stack
   stack_push(st, thing0); // This is a non-virtual call
   Stack.push(st, thing1); // This is like casting *st to a Stack (which it already is) and doing the push
   st->my_type.push(st, thing2); // This is a virtual call
}

我没有做析构函数或删除,但它遵循相同的模式。

This_is_here_as_an_example_only类似于一个静态类变量——在一个类型的所有实例之间共享。所有的方法都是静态的,除了一些采用this *