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How to make a program in metatrader.

  • #41
  • Edited 9:16pm Nov 28, 2008 7:19pm | Edited 9:16pm
Braces in general are used to contain multiple statements within a command. like
if(sometest)
{
statement 1;
statement 2;
}

or

for (int i=0;i<10;i++)
{
statement1;
statement2;
}

or

int i = 0;
while(i< 10)
{
statement1;
statement2;
i++;
}
  • #42
  • Edited 7:41pm Nov 28, 2008 7:25pm | Edited 7:41pm
Quoting smjones
Braces in general are used to contain multiple statements within a command. like
if(sometest)
{
statement 1;
statement 2;
}

or

for (int i=0;i<10;i++)
{
statement1;
statement2;
}

or

int i = 0;
while(i< 10)
{
statement1;
statement2;
i++
}
Okay

SetIndexBuffer(0, Buffer1);
Binds the array variable declared at a global level to the custom indicator pre-defined buffer.
Is this the predefined buffer? "#property indicator_buffers 1"

SetIndexStyle(0, DRAW_LINE,0,0,Red);
Here we choose the index, type, style, width and color.
What does it mean that index has to lie between 0 and 7. 0-7 what?

return(0)
A return operator terminates the current function execution with result transmission. Nothing is returned because we wrote (0) but if anything was returned where would it be saved?. I assume the reason for returning a result is to use it later so it must be saved somewhere so we can use it.

Time to go to bed now. It's 02:39 in my time zone. Good night.
If slaughterhouses had glass walls, everyone would be a vegetarian!
  • #43
  • Nov 28, 2008 7:42pm Nov 28, 2008 7:42pm
Quoting Gambler180
Okay

SetIndexBuffer(0, Buffer1);
Binds the array variable declared at a global level to the custom indicator pre-defined buffer.
Is this the predefined buffer? "#property indicator_buffers 1"

SetIndexStyle(0, DRAW_LINE,0,0,Red);
Here we choose the index, type, style, width and color.
What does it mean that index has to lie between...
Yes to the first question

Yes to the SetIndexStyle

yes 0 - 7 means the number of IndexBuffers you are allowed on a chart with one indicator. If you want more, you have to write more indicators for each 8 buffer thus 0 thru 7

Yes except you are actually returnig a zero.
In the case of the Init or the start. there is only an internal return. I will expalin more about this later, because it is more advanced than our discussion.
The reason to return a result is better explaind by an example. I am including EA I wrote that uses a custom function called GetFractals(int mode)
See what callse it and how it returns and you wil see what I meand
It is on my other computer, so give me a minute and come back to this post after I edit it to add the EA
  • #44
  • Nov 28, 2008 7:49pm Nov 28, 2008 7:49pm
PHP Code
//+------------------------------------------------------------------+
//|                                               NSWave EA v1.0.mq4 |
//|                                                                  |
//|                                                                  |
//+------------------------------------------------------------------+
#property copyright "Copyright © 2008, SjCoInc, All Rights Reserved"
#property link      "[email protected]"
extern int        Magic = 910;
extern double     Lots = 0.10;               // Used if AutoMoneyManagement = false
extern bool       AutoMoneyManagement = true;// Will automatically compute lots size based on PercentToRisk     
extern double     PercentToRisk = 1;         // Percent amount of balance to risk on trade
extern int        LookBack = 2;              // Bars back from current open to look for a Fractal
extern int        Slippage = 5;              // Amount of pip slippage allowed without causing a requote
extern bool       UseFractalForStop = true; // Uses the last fractal to the current open to compute StopLoss
extern double     MaximumStop = 35;          // Maximum allowable stop amount in pips
extern double     RR_Ratio = 2;              // Reward:risk ratio
extern double     Offset   = 0;              // distance above or below bar for stoploss
 
extern string     Note = "Trading hours are Broker time";
extern int        StartTrading = 7;          // Start of trading session
extern int        StopTrading = 17;          // end of trading session
string            Comments = "NSWave ";
datetime          timenowup = 0, timenowdn = 0;
//+------------------------------------------------------------------+
//| expert initialization function                                   |
//+------------------------------------------------------------------+
int init()
  {
//----
      Comment( "Copyright © 2008, SjCoInc" );
//----
   return(0);
  }
//+------------------------------------------------------------------+
//| expert deinitialization function                                 |
//+------------------------------------------------------------------+
int deinit()
  {
//----
 
//----
   return(0);
  }
//+------------------------------------------------------------------+
//| expert start function                                            |
//+------------------------------------------------------------------+
int start()
  {
//----
      double   Risk = PercentToRisk/100,StopLoss,TakeProfit;
 
      double   upfractal = GetFractal(MODE_UPPER),
               dnfractal = GetFractal(MODE_LOWER);
      if ( upfractal != 0 && timenowup != Time[0] && Hour() >= StartTrading && Hour() < StopTrading )
         {
            StopLoss = (High[1] - Close[1]+(Ask-Bid))/Point + Offset;
            if ( StopLoss > MaximumStop ) StopLoss = MaximumStop;
            if ( UseFractalForStop ) StopLoss = (upfractal - Bid)/Point+(Ask-Bid)+Offset;
            TakeProfit = NormalizeDouble(StopLoss * RR_Ratio, 0 );
            timenowup = Time[0];
            if (AutoMoneyManagement)
               Lots = NormalizeDouble(AccountBalance()*Risk/StopLoss/(MarketInfo(Symbol(), MODE_TICKVALUE)),2);
 
            OrderSend(Symbol(),OP_SELL,Lots,Bid,Slippage,Ask+StopLoss*Point,Bid-TakeProfit*Point, Comments+" Sell",Magic,0,Red);
            Comment("Upper ", upfractal, "   StopLoss ", StopLoss, "   TakeProfit ", TakeProfit, "   Lots ", Lots );
         }    
 
      if ( dnfractal != 0 && timenowdn != Time[0] && Hour() >= StartTrading && Hour() < StopTrading )
         {
            StopLoss = (Close[1] - Low[1]+(Ask-Bid))/Point + Offset;
            if ( StopLoss > MaximumStop ) StopLoss = MaximumStop;
            if ( UseFractalForStop ) StopLoss = (Bid - dnfractal)/Point+(Ask-Bid)+Offset;
            TakeProfit = NormalizeDouble(StopLoss * RR_Ratio, 0 );
            timenowdn = Time[0];
            if (AutoMoneyManagement)
               Lots = NormalizeDouble(AccountBalance()*Risk/StopLoss/(MarketInfo(Symbol(), MODE_TICKVALUE)),2);
 
            OrderSend(Symbol(),OP_BUY,Lots,Ask,Slippage,Bid-StopLoss*Point,Ask+TakeProfit*Point, Comments+" Buy",Magic,0,Lime); 
            Comment("Lower ", dnfractal, "   StopLoss ", StopLoss, "   TakeProfit ", TakeProfit, "   Lots ", Lots );
         }            
 
 
//----
   return(0);
  }
//+------------------------------------------------------------------+
double GetFractal(int mode)
   {
      double tempup=0, tempdn=0, fup=0, fdn=0;
      tempup = iFractals(Symbol(), 0, MODE_UPPER, LookBack);
      tempdn = iFractals(Symbol(), 0, MODE_LOWER, LookBack);
      if(tempup != 0) fup = tempup;
      if(tempdn != 0) fdn = tempdn;
      if ( fup != 0 && fdn == 0 && mode == MODE_UPPER ) return(fup);
      if ( fdn != 0 && fup == 0 && mode == MODE_LOWER ) return(fdn);
      return(0);
   }
See how the custom function GetFractal(int mode) is called by the varables upfractal and dnfractal and then assigned to them. this is where the return from GetFractal() went.
  • #45
  • Nov 28, 2008 7:56pm Nov 28, 2008 7:56pm
Now then, go to sleep. see you tomorrow.. LOL
  • #46
  • Nov 28, 2008 8:02pm Nov 28, 2008 8:02pm
If possible I am a little more confused now. Under start I see "
double upfractal = GetFractal(MODE_UPPER), dnfractal = GetFractal(MODE_LOWER);" but I don't see where the custom function "GetFractal" is defined. and every time you have written return there is a 0 in the parentheses. (0) = returns nothing if I have understood it right.
If slaughterhouses had glass walls, everyone would be a vegetarian!
  • #47
  • Nov 28, 2008 8:13pm Nov 28, 2008 8:13pm
Quoting Gambler180
If possible I am a little more confused now. Under start I see "
double upfractal = GetFractal(MODE_UPPER), dnfractal = GetFractal(MODE_LOWER);" but I don't see where the custom function "GetFractal" is defined. and every time you have written return there is a 0 in the parentheses. (0) = returns nothing if I have understood it right.
Look at the bottom of the program below the start function and you will find the custom function GetFractal(intmode)
The declaration of that function is the word double in front of the GetFractal() part. this declares it as a double, with global scope like an extern has. Please note that I could have put this at the top where the extern variables are just as easy. as it is in the global area and not located in any particular built in function like Init() or Start() or Deinit() also note that these are also in a global area and not nested in another function.

note that in the function GetFractal under one if() it is the return(fup) is returned and in another if() the return(fdn) is returned and when neither of these two if()s are true, the return(0) is returned to upfractal and dnfractal. So, a zero is returned when the two ifs are false.
  • #48
  • Nov 28, 2008 8:19pm Nov 28, 2008 8:19pm
In most modern programming languages it makes no difference in what order you place custom functions as long as they are in the global area.

The standard MT4 format that most people use is Init() then deInit() then start() then the customfunctions(). Some people put the custom functions() in between the deinit() and the start() but this is just their custom and not required in that order.
  • #49
  • Edited 8:56pm Nov 28, 2008 8:25pm | Edited 8:56pm
these are from another EA I wrote.

The first custom function here CloseTrades(int type) brings ins a int which can be either OP_BUY which is a 0 or OP_SELL which is a 1 and then does some work in tht it closes trades and then it returns nothing. so the return has no (0)

PHP Code
void CloseTrades(int type )
   {
      int totalorders = OrdersTotal();
 
      for(int n=totalorders-1;n>=0;n--)
         {
            OrderSelect(n, SELECT_BY_POS);
            //bool result = false;
            if ( OrderMagicNumber()== Magic ) 
               {
                  //Close opened long positions
                  if ( OrderType() == type && type == OP_BUY )OrderClose( OrderTicket(), OrderLots(), MarketInfo(OrderSymbol(), MODE_BID), 5, White );
                  //Close opened short positions
                  if ( OrderType() == type && type == OP_SELL )OrderClose( OrderTicket(), OrderLots(), MarketInfo(OrderSymbol(), MODE_ASK), 5, White );
                  //Close pending orders
                  //if ( OrderType() > 1 )result=  OrderDelete( OrderTicket() );
               }
         }
 
      return;
   } 
bool NoOpenOrders()
   {
      bool result = true;
      int totalorders = OrdersTotal();
      for(int n=totalorders-1;n>=0;n--)
         {
            OrderSelect(n, SELECT_BY_POS);
            if ( OrderMagicNumber() == Magic )
               result = false;
         }
      return(result);
   }



Notice that the first one is a void and just does some commands and the second one is a bool and returns a true or a false.

Edit:
Here is the EA that this is from. also note that it uses the iCustom() so it looks for the logic in the custom indicator listed. I will explain more about this later after we cover more of the basics. Anyway, to run this EA the indicator posted must be in the indcator folder and compiled.
Attached File(s)
File Type: mq4 FX Snipers T3 CCI.mq4   3 KB | 270 downloads
File Type: mq4 FXSniperT3CCIEA_v1.1.mq4   4 KB | 261 downloads
  • #50
  • Nov 28, 2008 8:25pm Nov 28, 2008 8:25pm
Quoting smjones
Look at the bottom of the program below the start function and you will find the custom function GetFractal(intmode)
The declaration of that function is the word double in front of the GetFractal() part. this declares it as a double, with global scope like an extern has. Please note that I could have put this at the top where the extern variables are just as easy. as it is in the global area and not located in any particular built in function like Init() or Start() or Deinit() also note that these are also in a global area and not nested in another...
Wow. That is smart. There is another thing I have been wondering about. under int init you have this code which shows some text on the screen.
Comment( "Copyright 2008, SjCoInc" );
What do I do if I want some text under that. I copied the code and pasted it below but the comment does not appear on the screen two times even though the code is written two times.
If slaughterhouses had glass walls, everyone would be a vegetarian!
  • #51
  • Edited 8:51pm Nov 28, 2008 8:30pm | Edited 8:51pm
Quoting Gambler180
Wow. That is smart. There is another thing I have been wondering about. under int init you have this code which shows some text on the screen.
Comment( "Copyright 2008, SjCoInc" );
What do I do if I want some text under that. I copied the code and pasted it below but the comment does not appear on the screen two times even thoug the code is written two times.
Comment can only be used once at a time. so if you have several things to say, the best way to say it is with string variables.

string var1 = "Hello World";
string var2 = "\n"; // this is a carriage return
string var3 = "I was here";

Comment ( var1, var2,var3);
result
Hello World
I was here

Also don't forget that the Init() only gets executed once. so if there is a Comment in the Start() the init() Comment will be overwritten
  • #52
  • Nov 28, 2008 9:03pm Nov 28, 2008 9:03pm
well now it has been 6 hours, so I am calling it a night. See you tomorrow.
  • #53
  • Nov 28, 2008 9:29pm Nov 28, 2008 9:29pm
One more thing, since you're the thread starter here. How about you change the title of this thread to something like How do I write a program in Metatrader?

Or something like that and then others can follow along and maybe we can help many at once. Or if you like keep it the same and I will just work with you. If you choose to change the title you can do that using ThreadTools and then edit thread options.
  • #54
  • Nov 28, 2008 9:35pm Nov 28, 2008 9:35pm
I would like to save two numbers in variables.
var1=10
var2=20
and in the third variable I wamnt the result
var3=var1+var2.
Then I would like to show the result with the comment function. How do I do that? Should I "use" int or "string" for the variables?
If slaughterhouses had glass walls, everyone would be a vegetarian!
  • #55
  • Nov 28, 2008 9:39pm Nov 28, 2008 9:39pm
Quoting Gambler180
I would like to save two numbers in variables.
int var1=10
int var2=20
and in the third variable I wamnt the result
int var3=var1+var2.
Then I would like to show the result with the comment function. How do I do that? Should I "use" int or "string" for the variables?
This is how I would do it.

Comment ( "var3 = ", var3);
or
Comment ("var1 + var2 = ", var3);
or
Comment (var1," + ",var2, " = ", var3);
or you can do it all in the Comment
int var1=10;
int var2=10;

Comment ( "var1 plus var2 = ", var1+var2 );
  • #56
  • Nov 28, 2008 9:39pm Nov 28, 2008 9:39pm
Quoting smjones
One more thing, since you're the thread starter here. How about you change the title of this thread to something like How do I write a program in Metatrader?

Or something like that and then others can follow along and maybe we can help many at once. Or if you like keep it the same and I will just work with you. If you choose to change the title you can do that using ThreadTools and then edit thread options.
I have just done that. It's fine if others join. I can probably also learn something from other peoples questions.
If slaughterhouses had glass walls, everyone would be a vegetarian!
  • #57
  • Nov 28, 2008 9:51pm Nov 28, 2008 9:51pm
Quoting Gambler180
I have this code but it does not work.

string var1="10";
string var2="20";
Comment ("var1 + var2 = ", var3);

It should only show the result (30).
You are mixingvaiable types.

it should be either int or double. these are numbers. string is a text variable.
int var1 = 10;
int var2 = 20;
int var3 = var1+var2;
Comment(Var1," + ", Var2, " = " , Var3);

Edit I have changed the answer I made a mistake. getting tired.
  • #58
  • Nov 28, 2008 9:58pm Nov 28, 2008 9:58pm
Quoting smjones
You are mixingvaiable types.

it should be either int or double. these are numbers. string is a text variable.
int var1 = 10;
int var2 = 20;
Comment(Var1," + ", Var2, " = " , Var3);
Oops. That is not good

This is working
int var1=10;
int var2=15;
int var3=var1+var2;

Comment (var3);

Am I right if I say that if I had numbers like 1,2456 then I have to use double instead of int?
If slaughterhouses had glass walls, everyone would be a vegetarian!
  • #59
  • Nov 28, 2008 10:01pm Nov 28, 2008 10:01pm
Quoting Gambler180
Oops. That is not good

This is working
int var1=10;
int var2=15;
int var3=var1+var2;

Comment (var3);

Am I right if I say that if I had numbers like 1,2456 then I have to use double instead of int?
yes, but in MT4 it is written 1.2456 not 1,2456

a double is for fractional numbers like 1.12345 it can also be used for a integer like 1 or 2 or 3
an int is for ONLY whole numbers.
  • #60
  • Nov 29, 2008 8:36am Nov 29, 2008 8:36am
Now I think I will write a function that will put various bits of information on the screen, such as:
Range Today =
Pip Value =
Account Balance =
Account Equity =

Then I am going to call that function in a indicator I am going to write. I could just put all of this in the start() but I want to get used to using functions. This makes following the logic in the start function much easier and keeps things neat.

As a reminder, in any program I write, whether it is a EA or a script or a indicator,
There is a Global area: this is where I declare external variable inputs that show up for user manipulation in the input window.
Also it is where I declare any other type of variable that I want ALL functions to have access to. These can be variables such as individual variables like
string "some text"; int MyInteger; double MyFracionalNumber; Bool MYYesNO;
color MyColorUsed; datetime MyTimeVariable;
or they can be Functions them selves like:
void Myworkfunction(); this does work and does not return a value so the
return; does not have a value (somenumber) at the end of it.
void Myworkfunction(OptionalInputs)
{
Comment("Hello World");
return;
}
int MyIntegerFunction(optional inputs, Optional inputs,...)
{

return(AnIntegerValueOnly);
}
Double MyDoubleFunction(Optionalinputs...)
{

return(ADoubleValueOnly);
}
string MyStringFunction(Optional Inputs...)
{

return(AStringValueOnly);
}
bool MyTureOrFalseFunction(OptionalInputs...)
{

return(ATrueOrFalseValueONLY);
}
Notice these functions are also in the global area, so they are available to all other functions, including the three built in functions that are MT4.
The first Built in Function of MT4 is
int init()
{

return(0);
}
This starts the indicator or EA or script up and is where you would place commands that you only want executed at the beginning of the program,
like drawing the prevoius data on the screen for each bar that are held in
array variables for each bar (we talked about this above) commands like
SetIndexBuffer and SetIndexStyle and SetIndexLable and SetIndexLevel

So now that we have began the program, we need to have a way of keeping it running with each new tick of data. So we have the
int start()
{

return(0);
}
This is where we place all the commands we want to have acted on with each new tick of data that comes in. In the init() we drew all of the prevoius bars of data held in the previous elements of the arrays we used in the for loop to fill up the array. Now we will act on the current data here and fill up the current element of the array here. Note that as we get each new tick, it can change the data that is stored in the current array element like
Buffer1[0] the [0] denotes the current element, this is now.
The start(); will just continue to run until it finds the return(0); command.
And then the start() will go back to the beginning and execute everything again until you tell it to stop by either removing the program from the chart or turning off MT4.
This is the heart of any program in MT4 This is where we call the custom functions we wrote if there are any.

Then there is the
int deinit()
{

return(0);
}
This built in function is the last function to run when we request the program to stop by either turning off MT4 or removing the program from the chart.
If you have anything you want executed only once at the end of the program it should go here. I will often put any print commands that I want written to the log file for the day that is held in the expert folder here. Things like the largest drawdown and time. or perhaps the largest pip spread and the time.
This way I have a permanent record of this information for each day.

So Lets begin to write this function. on the next post
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