I am novice, and I am working now in a proyect with the vga colour palette, over DOS with borland c 3.1.
The project include cpp.h and asm files. Sintactically I checked that is ok, BUT when I do the link tell me DECLARATION SYNTAX ERROR , in the first clase declared in the first h file in the project, I changed the place of the file but still continue give me the same error.

I send here one of the h files in which you can see that it is ok.

//MOUSE256.H

#ifndef __DOS_H
#include <dos.h>
#endif
#ifndef __STDLIB_H
#include <stdlib.h>
#endif
#ifndef _MOUSE256_H
#define _MOUSE256_H
#endif


//****************************************************************
// Class TMouse
//
// This class defines a group of functions and data structures
// which allow a DOS-based program to set up mouse-operated
// controls. A call-back mechanism allows regions of the
// screen to be defined which trigger calls to user-defined
// functions when the left mouse button is pressed and the
// cursor is within the defined region.
//
//****************************************************************

#define MOUSE_INT 51
#define BUTTON_DOWN 1
#define BUTTON_UP 0
#define BUTTON_LEFT 1
#define BUTTON_RIGHT 2
#define STANDARD_SET 1
#define NO_STANDARD 0
#define BUTTON_ENABLED 1
#define BUTTON_DISABLED 0
#define RUN_ENABLED 0
#define RUN_DISABLED 1

#define MC_RESET 0
#define MC_SHOWCURSOR 1
#define MC_HIDECURSOR 2
#define MC_GETSTATUS 3
#define MC_SETXLIMIT 7
#define MC_SETYLIMIT 8
#define MC_SETMICKEYS 15



class TMouse
{
private:
struct coord_t
{
int current_position;
int down_position;
int up_position;
int limit_min;
int limit_max;
} x,y;

struct button_t
{
int status;
int down_interval;
int up_interval;
} left,right;

struct list_t
{
int x_pos,y_pos;
int x_size,y_size;
int enable_flag;
int(*callback)();
struct list_t *next;
} list_head,*current_call,*list_tail;

union REGS inregs,outregs;
int standard_flag,run_flag,callback_count;
enum {TRUE,PROCESSED,FALSE} press_pending;

public:
TMouse();
~TMouse();
virtual int GetPositionX(void){return(x.current_position);};
virtual int GetPositionY(void){return(y.current_position);};
virtual void HideCursor();
virtual void ShowCursor();
virtual void SetMouseLimits(int,int,int,int);
virtual void SetStandardCallback(int(near*)());
virtual void SetCallback(int(near*)(),int,int,int,int);
virtual void DeleteCallback(int(near*)());
virtual void Run();
private:
void FlagReset();
void GetStatus();
void SetMickeysPerPixel(int,int);
} ;

This isn't #included by a C file, is it?

Good question Dave, but it's included

I mean, "Is the header file that you have shown above #included by a C file (*.c), or by a C++ file (*.cpp)?" If it is a C file, the class keyword will cause a Declaration syntax error.

No Dave, the extension of the c file is cpp (*.cpp), till this point is ok.