No. of People accessing a file

[Algren]

I have made a code which runs a chat on the same computer, where all users are logged in on the same machine/server/etc. What is the problem is that i want to show the user how many people are logged into a particular chatroom/file. I could put a code at the end which decrements the no. of users, but i want those who close the program to be taken into account too.

Heres the code if you need it:

#include<fstream.h>
#include<iostream.h>
#include<conio.h>
#include<stdlib.h>
#include<stdio.h>
#include<string.h>
#include<dos.h>

void main()
{

 clrscr();

 fstream F;

 char name[15], chat[100], room[12];

 int ch, post=0, n=0, hut=0;

 cout<<"Enter ur screen name: "; cin>>name;
 cout<<"Enter Room Name: "; cin>>room;

 changeroom:

 strcat(room,".txt");

 F.open(room,ios::app);

 F<<endl<<endl<<"*** "<<name<<" has just joined the chat ***"<<endl;

 F.close();

 while(1)
 {
  delay(60);
  hut++;
  clrscr();

  char STR[102];


  //CHAT DISPLAY

  F.open(room,ios::in);


  while(!F.eof())
  {
   F.getline(STR,102);
   cout<<STR<<endl;
  }

  F.close();

  //USER INPUT

  char colon[102]=": ", whencename[117];

  strcpy(whencename,name);

  cout<<"--------------------------------------------------------------------------------"<<endl<<name<<colon<<chat;

  if(kbhit())
  {
   ch=getch();
   if((ch!=8)&&(ch!=13)){ chat[n++]=ch; chat[n]='\0';}
   else if(ch==13) post=1;
   else if (n>0) chat[--n]='\0';
   else chat[0]='\0';

  }

  if(post)
  {
   post--;

   if(strcmpi("/truncate",chat)==0)
   {
    ofstream Fdelete(room);
    Fdelete.close();
   }
   else if(strcmpi("/name",chat)==0)
   {
    cout<<"\n\n\tEnter New Name: "; cin>>name;
   }
   else if(strcmpi("/room",chat)==0)
   {
    cout<<"\n\n\tEnter New Room: ";cin>>room;
    n=0; chat[0]='\0';
    goto changeroom;
   }
   else
   {
    strcat(colon,chat);

    strcat(whencename,colon);

    F.open(room,ios::app);

    F<<endl<<whencename;

    F.close();
   }
   n=0; chat[0]='\0';

  }



 }
 getch();
}

I know its the good-old TC code, replace void main with int main, and add using namespace std; before main to run in modern compilers.