The interface is a special class that is not implemented, it is a collection of operations, we can think of it as an agreement with other objects. There is no keyword such as Interface in C to define interfaces, but the __Declspec (NOVTABLE) is provided in Mircrosoft C to modify a class, which means that the class has no virtual functions, that is, the virtual function is pure. So use it we can still define an interface. The code example is as follows:
#include
<
Iostream
>
Using
Namespace
STD;
#define
Interface class __declspec (novTable)
Interface
ICODEC {
public
:
Virtual
Bool
Decode
charr
*
LPDataSRC, unsigned
int
Nsrclen,
charr
*
LPDATADST, UNSIGNED
int
*
Pndstlen;
Virtual
Bool
ENCODE
charr
*
LPDataSRC, unsigned
int
Nsrclen,
charr
*
LPDATADST, UNSIGNED
int
*
Pndstlen;
Class
CCODEC:
public
ICODEC {
public
:
Virtual
Bool
Decode
charr
*
LPDataSRC, unsigned
int
Nsrclen,
charr
*
LPDATADST, UNSIGNED
int
*
Pndstlen) {cout
<<
"
decoding...
"
<<
ENDL;
Return
True
}
Virtual
Bool
ENCODE
charr
*
LPDataSRC, unsigned
int
Nsrclen,
charr
*
LPDATADST, UNSIGNED
int
*
Pndstlen) {cout
<<
"
coding...
"
<<
ENDL;
Return
True
;}};
int
Main
int
Argc,
charr
*
Argv []) {icodec
*
PCODEC
=
New
Ccodec (); pcodec
->
Decode (NULL,
0
, Null, null; PCODEC
->
ENCODE (NULL,
0
, Null, null; delete (CCODEC
*
PCODEC;
Return
0
}
The above ICODEC interface is equivalent to the following definition:
Class
ICODEC {
public
:
Virtual
Bool
Decode
charr
*
LPDataSRC, unsigned
int
Nsrclen,
charr
*
LPDATADST, UNSIGNED
int
*
Pndstlen
=
0
;
Virtual
Bool
ENCODE
charr
*
LPDataSRC, unsigned
int
Nsrclen,
charr
*
LPDATADST, UNSIGNED
int
*
Pndstlen
=
0
};
related articles:
What is the __Declspec in the VC - preface
Chapter 1 of the "__Declspec" in the VC (1) - Definition Interface
