Encapsulation and information hiding with pure C language

shifter · 06-20-2013, 03:00 PM

In what way is it possible to use encapsulation and information hiding principles with C language? (without considering Object Oriented paradigm and C++)

NevemTeve · 06-20-2013, 03:14 PM

A well-known method for opaque data-types is the following:

Code:

/* somestuff.h */

typedef struct Stuff Stuff;

extern Stuff *StuffConstruct (int param);
extern void StuffDestruct (Stuff *); 

... other methods ...

Code:

/* somestuff.c */

#include "somestuff.h"

struct Stuff {
...
};

Stuff *StuffConstruct (int param)
{
    Stuff *ptr= malloc (sizeof (*ptr));
    ...
    return ptr;
}

void StuffDestruct (Stuff *ptr)
{
    ...
    free (ptr); 
}

... other methods ...

shifter · 06-20-2013, 04:17 PM

Why did you declare functions as "extern" in header file?

ta0kira · 06-20-2013, 09:48 PM

It isn't necessary in this case, but it's often used to indicate that the function is going to be defined in another file (as opposed to later in the same file.) On the other hand, you would need to use extern for a global variable made available by the header to make it a declaration rather than a definition.

Kevin Barry

NevemTeve · 06-21-2013, 03:53 AM

Everything else is clear?

shifter · 06-21-2013, 04:29 AM

Ok, now everything is clear, thank you very much!