could you explain this mistake?

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Hi all, could you explain why it's wrong this way to recall the orders? 

Thank you!

 total = OrdersTotal();   
  for(cnt=0;cnt<=total;cnt++)
     {    
     OrderSelect(cnt, SELECT_BY_POS, MODE_TRADES);
     if (OrderSymbol()==Symbol() )      
        {
        ...      


 
Alberto Tortella:


Hi all, could you explain why it's wrong this way to recall the orders? 

Thank you!


OrdersTotal starts at 0. 
for(cnt=0;cnt<total;cnt++)
 

Hi,

The function OrdersTotal() gives you the number of open and pending orders.

The function OrderSelect() start from 0 to OrdersTotal()-1.

That's why, as says Icham, you have to write :

for(cnt=0;cnt<total;cnt++)
  
 total = OrdersTotal();   
  for(cnt=0;cnt<=total;cnt++)
     {    
     OrderSelect(cnt, SELECT_BY_POS, MODE_TRADES);
     if (OrderSymbol()==Symbol() )      
        {
        ...      
  1. In the presence of multiple orders (one EA multiple charts, multiple EAs, manual trading,) while you are waiting for the current operation (closing, deleting, modifying) to complete, any number of other operations on other orders could have concurrently happened and changed the position indexing:
    1. For non-FIFO (US brokers,) (or the EA only opens one order per symbol,) you can simply count down in a position loop, and you won't miss orders. Get in the habit of always counting down.
                Loops and Closing or Deleting Orders - MQL4 and MetaTrader 4 - MQL4 programming forum
      For FIFO (US brokers,) and you (potentially) process multiple orders per symbol, you must count up and on a successful operation, reprocess all positions (set index to -1 before continuing.)
    2. and check OrderSelect in case earlier positions were deleted.
                What are Function return values ? How do I use them ? - MQL4 and MetaTrader 4 - MQL4 programming forum
                Common Errors in MQL4 Programs and How to Avoid Them - MQL4 Articles
    3. and if you (potentially) process multiple orders, must call RefreshRates() after server calls if you want to use the Predefined Variables (Bid/Ask) or OrderClosePrice() instead, on the next order/server call.

  2. Using OrdersTotal directly and/or no Magic number filtering on your OrderSelect loop means your code is incompatible with every EA (including itself on other charts and manual trading.)
              Symbol Doesn't equal Ordersymbol when another currency is added to another seperate chart . - MQL4 and MetaTrader 4 - MQL4 programming forum

  3. If there are n orders, they are positions [0 .. n-1] your last iteration will always fail, but you don't check.
 
Alberto Tortella:


Hi all, could you explain why it's wrong this way to recall the orders? 

Thank you!



total = OrdersTotal()-1;   
for(cnt=0;cnt<=total;cnt++)
{
  //

}
  
total = OrdersTotal()-1;   
for(cnt=0;cnt<=total;cnt++)
What part of #3.1.1 was unclear?
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