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MQL4 custom Function

  • #1
  • First Post: Sep 16, 2012 7:19pm Sep 16, 2012 7:19pm
Hello Folks,

I'm trying to do my own custom function to show me open Orders (Buy+Sell). This code works, but lacks some things.

Inserted Code
void OpenOrders ()
   {
   BuyOrdersOpen = 0;
   SellOrdersOpen = 0;
   int               TotalOrders;
   TotalOrders = OrdersTotal();
   for(int iii=TotalOrders-1;iii>=0;iii--)
      {
        OrderSelect(iii, SELECT_BY_POS);
      if(OrderSymbol() != Symbol()) continue;
      if(OrderType() == OP_BUY)
         {
         BuyOrdersOpen = BuyOrdersOpen + 1;
         }
      if (OrderType() == OP_SELL)
         {
         SellOrdersOpen = SellOrdersOpen + 1;
         }
      }
   }
My Problem so far is that I work with global variables to get the results from the function (BuyOrdersOpen, SellOrdersOpen). I know I can somehow make the function return the values and have the values available, if I just call the function right. Don't know how to get there however...

Can anybody help me out?
  • #2
  • Sep 16, 2012 8:05pm Sep 16, 2012 8:05pm
Quoting MikeFT
Hello Folks,

I'm trying to do my own custom function to show me open Orders (Buy+Sell). This code works, but lacks some things.

[code]void OpenOrders ()
{
BuyOrdersOpen = 0;
SellOrdersOpen = 0;
int TotalOrders;
TotalOrders = OrdersTotal();
for(int iii=TotalOrders-1;iii>=0;iii--)
{
OrderSelect(iii, SELECT_BY_POS);
if(OrderSymbol() != Symbol()) continue;
if(OrderType() == OP_BUY)
{
BuyOrdersOpen = BuyOrdersOpen + 1;
}
if (OrderType() == OP_SELL)
{...
look-up in the help file "return".

you've now asked a couple of very rookie programming questions lately. perhaps you should put down the mql and do some light reading on something like qbasic or python or something along those lines... or if you can find a decent C tutorial. you just can't keep coming here to ask what sound like homework questions. mql is pretty shit for trying to learn how to do anything code-related. it's half c-like and half something abstract, and the help file is in broken english that usually makes little sense.

go read about some other language. play with it. then come back to mql. then you might have some mql-specific questions instead of banging your head against the basics and asking everyone here.

a good programmer doesn't have to know every little function provided by a language. they just need to understand the fundamentals of how the language operates, and then know how to find in help files (and online) the specifics of all of the other things that can be done. you need to learn about and understand the fundamentals... mql is not the place to start.

hell, maybe even something like robotbattle would be a starter. at least it might be semi-interesting (and then core wars if you really get into things and progress from a coding rookie to a bit more advanced).

edit : and to follow from codemeister.... also look into passing variables by reference or by value.
Congratulations ScalaFX for coming out of the closet!
  • #3
  • Sep 16, 2012 8:05pm Sep 16, 2012 8:05pm
The problem with MQL (and other language) functions is that they only return a single value. I find myself in the same conundrum from time to time. Using globals is not a bad choice considering some of the alternatives. Some would suggest using 2 functions, one that returns the number of Buy and another for the sells. But that means calling both every time plus the duplication of code. I have seen some people return one value as the function value and the other as a global - ugly code and doesn't make any sense.
  • #4
  • Sep 16, 2012 11:06pm Sep 16, 2012 11:06pm
Maybe I'm just old school - I learned C before I learned MQL - but the solution to this problem has been around since... well C, I guess.

http://docs.mql4.com/basis/variables/formal
  • #5
  • Sep 19, 2012 2:33am Sep 19, 2012 2:33am
Quoting MikeFT
Hello Folks,
I'm trying to do my own custom function to show me open Orders (Buy+Sell). This code works, but lacks some things.
Something like this (passing parameters by reference) and returning the total? This way you get all three values: buyopenorders, sellopenorders (by reference from the parameter list) and the value of totalopenorders returned from the function.

Also, note the changes to the indentation. The goal of indentation is to show where blocks of code start and end (like loops or if blocks) for easy visual inspection. Make sure your curly brackets frame the blocks properly. Properly means the curly bracket lines up (left justified) with the associated for loop or if block. Code inside the block (inside the curly brackets) is indented.
Inserted Code
int OpenOrders (int BuyOrdersOpen&, int SellOrdersOpen&)
{
   BuyOrdersOpen = 0;
   SellOrdersOpen = 0;
   int TotalOrders = OrdersTotal();
   for(int iii=TotalOrders-1;iii>=0;iii--)
   {
      OrderSelect(iii, SELECT_BY_POS);
      if(OrderSymbol() != Symbol()) continue;
      if(OrderType() == OP_BUY)
      {
         BuyOrdersOpen += 1;
      }
      if (OrderType() == OP_SELL)
      {
         SellOrdersOpen += 1;
      }
   }
   return TotalOrders;
}
  • #6
  • Sep 19, 2012 2:41am Sep 19, 2012 2:41am
Quoting CodeMeister
The problem with MQL (and other language) functions is that they only return a single value. I find myself in the same conundrum from time to time. Using globals is not a bad choice considering some of the alternatives. Some would suggest using 2 functions, one that returns the number of Buy and another for the sells. But that means calling both every time plus the duplication of code. I have seen some people return one value as the function value and the other as a global - ugly code and doesn't make any sense.
I hear the concern. I tend to think that repeating code (particulary loops) is often a bad idea. MT4 is inefficient enough as it is, no need to help it be less efficient. However, passing parameters by reference may make reading / understanding the code more difficult for some or in some cases. If it does this then it may be worth the performance hit, or the use of a global variable which I prefer over repeating loops.

My preference is to do a single loop whenever possible and to pass references as in the code above. Globals also work but then it becomes less clear what is a reusable function and what is fragile code. Not that I don't use a global variable often by design. Sometimes making the code reusable or generalized is more effort than it is worth. I don't reuse everything.
  • #7
  • Sep 19, 2012 2:54am Sep 19, 2012 2:54am
Quoting FXEZ
Something like this (passing parameters by reference) and returning the total? This way you get all three values: buyopenorders, sellopenorders (by reference from the parameter list) and the value of totalopenorders returned from the function.

Also, note the changes to the indentation. The goal of indentation is to show where blocks of code start and end (like loops or if blocks) for easy visual inspection. Make sure your curly brackets frame the blocks properly. Properly means the curly bracket lines up (left justified) with the associated for...
i guess you aren't much into the whole 'teach a man to fish' concept and are more into just giving the fish away to anyone who asks.

and that indentation hurts my head. i know many do it like that, but i'm more of a 1TBS style myself. after a few thousand lines of code in 1TBS those wasted opening braces would have really added-up to a lot of extra wasted lines hindering readability significantly. just an idle observation since this thread is now basically finished. k&r indentation should be on the way out these days (according to me at least).
Congratulations ScalaFX for coming out of the closet!
  • #8
  • Last Post: Sep 19, 2012 3:17am Sep 19, 2012 3:17am
Quoting nubcake
i guess you aren't much into the whole 'teach a man to fish' concept and are more into just giving the fish away to anyone who asks.
I'm all about teaching a person to fish, but I felt he made an honest effort based on what code was posted and what was asked. He knew what he didn't know and was not too proud to ask for help.

Quote
and that indentation hurts my head. i know many do it like that, but i'm more of a 1TBS style myself. after a few thousand lines of code in 1TBS those wasted opening braces would have really added-up to a lot of extra wasted lines hindering readability significantly. just an idle observation since this thread is now basically finished. k&r indentation should be on the way out these days (according to me at least).

I also prefer 1TBS due to screen economy but as Mike was having difficulty just lining up the brackets, I didn't want to blow his mind.
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