Error: *&*$%$.o Multiply Defined

I am using the GNU compiler and make utility for UNIX. I have added the "#ifndef wrapper" to my header file that is supposed to take care of this problem. What I have is three code files, each of which requires the same header file. I have #include'd this header into each code file. Can anyone think of any common silly errors that I am making that I can't seem to figure out.

do you define any variables, or functions in the header such as

int x = 10;
or
void function(void)
{
// do something
}

instead of

int x;
const int x;
void function(void); // defined elsewhere
or
inline void function(void)
{
// do small something
}

Here is my header, there is one int and one Macro actually initialized but they are not the ones the compiler is complaining about. It is complaining about Client() and Server().


#ifndef HEADER_H_USED
#define HEADER_H_USED

#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <strings.h>

#define ReportError(msg) {perror(msg); exit(-1);}

int random(), M= 2147483647;
int srandom(unsigned);
void IntroduceError(char*, double);
char *GenerateData(int);
int Server(), Client();
double floor();
char linebuffer[100];

#endif

I have included this header in 3 files.

I don't know if it matters or not, but the functions Client.c and Server.c have this same header file included.

> M= 2147483647
You can't have these in a header file
You should have
&nbsp; extern int M;
Then initialise it in one of your .c files

> int Server(), Client();
Try
int Server();
int Client();

> double floor();
This is in math.h - why is it here?

> int random();
> int srandom(unsigned);
These are in stdlib.h (which you already include)

> char linebuffer[100];
Could be
extern char linebuffer[100];

Thanks for your help! I got that header file from my professor...