Hi, I have a problem with c files.
I have broken my code to 2 files main.c and unp.h

unp.h

typedef void (*Ptr_To_Function)(void);

struct Menu_Record
{
    unsigned int option_number;
    const char * text;
    Ptr_To_Function process_function;
};

struct Menu_Record* select(struct Menu_Record*,int);

struct Menu_Record startup[] =
{
    {1, "Choice1", NULL},
    {2, "Choice2",NULL},
    {0, "Exit", NULL}
};

main.c

#include <stdio.h>                                                      
#include <stdlib.h>	
#include <string.h>	
#include <errno.h>  

#include "unp.h" 


int main()
{
return 0;
}

struct Menu_Record* select(struct Menu_Record* menu, int num_options)
{
}

But when I compile I take errors

In file included from main.c:6:
unp.h:10: error: conflicting types for Α select Α
/usr/include/sys/select.h:109: note: previous declaration of Α select Α was he
re
client.c:57: error: conflicting types for Α select Α
/usr/include/sys/select.h:109: note: previous declaration of Α select Α was he
re

Never declare data objects in a header file because if you include the same header file in multiple *.c or *.cpp files the compiler will generate multiple declaration errors. So you want to move lines 12 - 17 of that header file into the *.c file (about line 7).

The key piece of information is the location of select(): "/usr/include/sys/select.h". This is the POSIX version, which means it's being linked automatically and you need to rename your select() function to avoid conflicting with it.