ssize_t sendfile - error

#define WorkPATH "a.txt"
#define NewWorkPATH "NEWa.txt"
int fd,length=0;
int fdnew;
int size;
char read_buffer[80];
char write_buffer[]="dddddddddddddddddddddddddddddddddd";

ssize_t sendfile(NewWorkPATH, WorkPATH, 0, sizeof (read_buffer));

the error:

error: expected declaration specifiers or ‘...’ before string constant
error: expected declaration specifiers or ‘...’ before string constant
error: expected declaration specifiers or ‘...’ before ‘&’ token
error: expected declaration specifiers or ‘...’ before ‘sizeof’

ssize_t sendfile - transfering data from one file to another
Stop with the new threads....