some programming help please

if( OrdersTotal() >= 8 )
    if( OrderSelect(0, SELECT_BY_POS) )
        OrderClose(OrderTicket(), OrderLots(), OrderClosePrice(), 3);

No, it's incorrect.

1. Check number of open orders.
2. If number greater then 8 --> find oldest order and remember its ticket.
3. Close order with this ticket.

I want to close the oldest market order if there are >=8 market orders,  but to ignore all the pending orders

  extern int Magic = ...
 
  //-----
 
  int BuyCnt = 0;
  int SellCnt = 0;
  
  int cnt = OrdersTotal();
  for (int i=0; i < cnt; i++) 
  {
    if (!OrderSelect(i, SELECT_BY_POS, MODE_TRADES)) continue;
    if (OrderSymbol() != Symbol()) continue;
    if (OrderMagicNumber() != Magic) continue;
    
    int type = OrderType();
    if (type == OP_BUY) BuyCnt++;
    if (type == OP_SELL) SellCnt++;
  }
  
  if (BuyCnt+SellCnt < 8) return;
 
  //-----
 
  datetime tm = 0;
  int ticket = -1;
 
  cnt = OrdersTotal();
  for (i=0; i < cnt; i++) 
  {
    if (!OrderSelect(i, SELECT_BY_POS, MODE_TRADES)) continue;
    if (OrderSymbol() != Symbol()) continue;
    if (OrderMagicNumber() != Magic) continue;
    
    type = OrderType();
    if (type == OP_BUY || type == OP_SELL)
    {
      if (OrderOpenTime() > tm)
      {
        tm = OrderOpenTime();
        ticket = OrderTicket();
      }
    }
  }
 
  //-----
 
  if (ticket != -1) OrderClose(ticket, ...

What to put here
extern int Magic = ...

and here
if (ticket != -1) OrderClose(ticket, ...

?

12345 for example.


RTFM

Okay it works thanks

int close_trade_ticket;
 
int start()
 {
  if (closeTrade(8, 5, 0, 0))
   Print ("Order closed with ticket number "+close_trade_ticket);
  else if (close_trade_ticket > 0)
   Print ("Unsuccessful closing order with ticket number "+close_trade_ticket);
  return(0);
 }
 
bool closeTrade (int oldest, int times_to_retry, int type, int Magic)
 {
  int opened_trades,count,ticket_time=TimeCurrent();
  close_trade_ticket=0;
  bool result;
  double price;
 
  for (int i=0; i < OrdersTotal(); i++) 
   {
    if (!OrderSelect(i, SELECT_BY_POS, MODE_TRADES)) continue;
    if (OrderSymbol() == Symbol() && OrderMagicNumber() == Magic)
     {
      if (OrderType() == OP_BUY || OrderType() == OP_SELL)
       {
        opened_trades++;
        if (OrderOpenTime() < ticket_time)
         {
          close_trade_ticket=OrderTicket();
          ticket_time=OrderOpenTime();
         {
       }
     }
   }
 
  if (opened_trades>=oldest) 
   {
    if(!IsTesting()) price=MarketInfo(Symbol(),9+OrderType());
    else
     {
      if (OrderType() == OP_BUY) price=Bid;
      else price=Ask;
     }
 
    while(!result)
     {
      result=OrderClose ( close_trade_ticket, OrderLots(), price, 0);
      count++;
      if (count >= times_to_retry) break;
     }
   }
   
  else close_trade_ticket=0;
 
  return(result);
 }

Thanks Rosh.
So you're saying that the orders in the pool are not stored in any particular order?
How about the ticket number. Is it monotonic increasing or just some random but unique number?

Tickets numbers are monotonic increasing and always are unique.