Learn New MQL Coding

ok, so now what to do, i got from internet, mq4 tool is good, i want to use it on renko.

ok, thnx sir i got it from internet, but i want to use it on renko chart.

Anyone know how to code an ea that is when a new white bar is formed, ea will close all my pending sell order... looking forward to
any pro programmer's advisee.. helpppp and thanksssss

Hi Weisik123, I doubt anyone will code a whole EA for you unless you post in the "I will code your EA for free thread" but you will need to be more specific or show existing code. If you just looking to be pointed in the right direction, you will need to include something like this in your code:



#define IsPendingOrder(type) ((type)>OP_SELL)
...
for(int i = limit; i > 0; i--){
if close[i]>open[i];
if ( IsPendingOrder(type) ) result=OrderDelete(OrderTicket());
}

I'm tiring to write a little EA, It has a code block as below, Which I'm trying to show reduce some pips from current price and show.
Ex -
GBPUSD
target pips=240
current price = 1.3380
target price=1.3380-(240/10000)
answer is 1.3140

my line code below

Comment("---Account Summery---", " Target Price ",((MarketInfo("GBPUSD",MODE_BID)) - (tgty / 100))));

It show errors when compile
'/' - illegal operation use
'-' - illegal operation use

anyone know how to fix this error please

Hi,
why does this cause the compiler to cry:
Can't I call the constructor from within another constructor?

I solved the problem by having both classes CI and CQ in the same file..

Hi,

I commonly use classes in MQL4 and often have this problem:
List Functions in Metaeditor (Alt + M) doesn't show some classes.

Thanks in advance.

Yeah if you do instantiate CQ, then the compiler must know its implementation, because the class has members that must be known before allocation. The forward declaration is not enough, unless you just work with pointers.

I'm trying to compile a indicator which shows a error
'.' - semicolon expected +++++ FX-Agency Advisor II +++++.mq4 22 17

when i go to line it has below code, anyone know why this error happening and solution for this

"." causes error

use

extern bool Show_Alerts = TRUE;

Thanks you for replay, the code have too many same . separated strings as above, will that ok to replace those with _

Hi, Broketrader, thanks for your great contribution! I really love to learn from you! thanks and happy new year!

I took a long break from MQL and recently picked it up again. A lot has changed; mostly for the better. I want to point out a few things and I think this is the best thread to express my ideas.

1. I came to this thread looking for some answers and ideas. I didn't find my answers but I gained a much greater depth of insight into the new MQL than I got from the Metaquotes website. This thread is one of the best here on FF and that is due to the diligence of Broketrade. As a software professional, I can appreciate the effort it took to put together a thread of this scope. Its too bad FF doesn't have a better thread rating system. This one deserves 5 stars and there aren't many others.

2. The new MQL MT5 upgrade path is so much better than the original one. I was able to recompile all of my old code with no errors and it just works. I took the time to incorporate the MQL5 style into the new code I wrote and found it easy, though not as intuitive as the old. I didn't go as far as making it Object Oriented, but that is on the path forward. So I consider most of the negativity surrounding MQL5 and MT5 to be rubbish. A lot has changed in the last 15 years and a lot more will change in the next 15. We as coders have to get on with it.

Not all old code will compile without modification.

To clarify, I didn't try to convert any EAs - they were failures and /or badly out of date.

Still I'm not convinced that upgrading will require much effort once the new MQL is learned. No need for a silver bullet solution like some are suggesting.

Thanks you very much for this adorable course in MQL OOP.

Great stuff！Thanks！

Hi, I'm not posting a lot these days as I'am very busy with other matters. At least, I wanted to say thank you to all for your kind comments.

Cheers,
BT

Hi people,

If there is still anybody interested in these coding matters (advanced object-oriented coding in mql) here around, after all this time...
Well, I wanted just to say that I have made some little progresses in the meanwhile, such that now I have my own platform, that I call mql evolution, which is a completely object-oriented mql based upon a library that I have written on top of mql4, which acts as an interface to the native mql and allows me to program over it. Actually performance of the system is even better than the native language, such that for instance backtesting a copy of an EA on "native" mql4 takes longer than the same logic re-coded on the mql evolution... but that's just a side topic.

For the interested I wanted to show here the template of what is known as a design pattern, i.e. a mechanism for coding the solution of a particular set of problems. This is the state design pattern, which is suitable for solving problems in which you have sort of "machine" changing behavior according to some "states". In trading systems this can happen for instance when you have to perform quite defined and different things when you have pending orders versus when orders are filled, or when you are waiting for the start time of a trading session versus when the trading session is ongoing or the like. In such cases, often, in procedural languages you start coding a series of "spaghetti" stuff like nested "if" statements or "switch" series. If the algorithm is complex, you end up with thousand lines, and, at least this is myself, at the end you don't remember what you have written two hours before, debugging takes longer than writing the code, and if you have to interrupt for two days, it takes you one week to understand what you were doing up to that point...

Good. I have posted the model for such a design pattern in mql4/5 on the mql community (I hope I can post the direct link on forex factory: it's for "educational purposes, isn't it moderators? https://www.mql5.com/en/forum/156109#comment_4983864). There you find the complete code listing and an output example).

If you want some more explanation about the pattern google "state design pattern". For an introduction to design patterns in general I would suggest the book "Head first design patterns" (google again): it is based on java, but, as soon as you get a bit familiar with mql4/5 object-oriented programming, you will see that the step to C++ (at least the fundamentals) is quite short, and from there you will see that the fundamentals of java are really very short. You will start seeing that the "big picture" of the whole is sort of a "common language". You will not be able to "program" in every one of these languages, because the "syntax" has its tricks and computers do not forgive a single comma. But you wll be able to "read" and "understand" what computers "say" because we, humans, are much smarter than computers!