Create your own MetaTrader extension (dll) - page 13
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The only way to do that using metatrader is to create an array, pass it by reference to the dll function and fill that array. Metatrader does not accept arrays as return values from dll functions
OK, Thanks
I have some problem with mql#.
Here not problem code for c#.
using System; using System.Text; using RGiesecke.DllExport; using System.Runtime.InteropServices; using System.Windows.Forms; namespace shine { class Test { [DllExport("AddDouble", CallingConvention = CallingConvention.StdCall)] public static double AddDouble() { System.MetaTrader hano = new MetaTrader(); double Values1 = hano.iCustom(hano.Symbol(), 0, "Borohul", 60, 50, 6, 1.3, true, true, false, false, true, false, false, 1, 0); return (Values1); } } }[/CODE]
Here mql code.
[CODE]
//+------------------------------------------------------------------+ //| testDLL.mq4 | //| Copyright © 2011, Patrick M. White | //| https://sites.google.com/site/marketformula/ | //+------------------------------------------------------------------+ #property copyright "Copyright © 2011, Patrick M. White" #property link "https://sites.google.com/site/marketformula/" #import "testUMD600.dll" double AddDouble(); #import //+------------------------------------------------------------------+ //| script program start function | //+------------------------------------------------------------------+ int start() { //---- Alert(AddDouble()); //---- return(0); } //+------------------------------------------------------------------+But when I testing live chart, then Metatrader platform close automatically. Why for me?
Rule of thumb, always handle errors inside each DLL function in C#. Failure to do so will cause the effect you are seeing where Metatrader closes down automatically. Put in a try / catch block in each public dll function and you will be able to see what is causing the problem. It is probably an unhandled error in your dll feeding back to Metatrader causing it to shut down. Error handling and dealing with errors is the most difficult part of the C# to MT4 dll process. I don't check this forum often so ask questions as comments on the blog so I get a notification and can answer in a more timely manner.
Here not problem code for c#.
using System; using System.Text; using RGiesecke.DllExport; using System.Runtime.InteropServices; using System.Windows.Forms; namespace shine { class Test { [DllExport("AddDouble", CallingConvention = CallingConvention.StdCall)] public static double AddDouble() { System.MetaTrader hano = new MetaTrader(); double Values1 = hano.iCustom(hano.Symbol(), 0, "Borohul", 60, 50, 6, 1.3, true, true, false, false, true, false, false, 1, 0); return (Values1); } } }[/CODE]
Here mql code.
[CODE]
//+------------------------------------------------------------------+ //| testDLL.mq4 | //| Copyright © 2011, Patrick M. White | //| https://sites.google.com/site/marketformula/ | //+------------------------------------------------------------------+ #property copyright "Copyright © 2011, Patrick M. White" #property link "https://sites.google.com/site/marketformula/" #import "testUMD600.dll" double AddDouble(); #import //+------------------------------------------------------------------+ //| script program start function | //+------------------------------------------------------------------+ int start() { //---- Alert(AddDouble()); //---- return(0); } //+------------------------------------------------------------------+Here not problem code for c#.
using System; using System.Text; using RGiesecke.DllExport; using System.Runtime.InteropServices; using System.Windows.Forms; namespace shine { class Test { [DllExport("AddDouble", CallingConvention = CallingConvention.StdCall)] public static double AddDouble() { System.MetaTrader hano = new MetaTrader(); double Values1 = hano.iCustom(hano.Symbol(), 0, "Borohul", 60, 50, 6, 1.3, true, true, false, false, true, false, false, 1, 0); return (Values1); } } }[/CODE]
Here mql code.
[CODE]
//+------------------------------------------------------------------+ //| testDLL.mq4 | //| Copyright © 2011, Patrick M. White | //| https://sites.google.com/site/marketformula/ | //+------------------------------------------------------------------+ #property copyright "Copyright © 2011, Patrick M. White" #property link "https://sites.google.com/site/marketformula/" #import "testUMD600.dll" double AddDouble(); #import //+------------------------------------------------------------------+ //| script program start function | //+------------------------------------------------------------------+ int start() { //---- Alert(AddDouble()); //---- return(0); } //+------------------------------------------------------------------+any example where it worked with old version?
Probably protection problem
Rule of thumb, always handle errors inside each DLL function in C#. Failure to do so will cause the effect you are seeing where Metatrader closes down automatically. Put in a try / catch block in each public dll function and you will be able to see what is causing the problem. It is probably an unhandled error in your dll feeding back to Metatrader causing it to shut down. Error handling and dealing with errors is the most difficult part of the C# to MT4 dll process. I don't check this forum often so ask questions as comments on the blog so I get a notification and can answer in a more timely manner.
Just from that code it can not be determined why (maybe the problem is in some of the using resources)
Hi guys,
I try to get a DLL indicator / MT4 running... It's the code for a recursive SMA, but I don't get it working. I got it from a blog.
Has anybody an idea why / where is the fault?
DLL file is written in C++ and compiles (as project) in VC 2010 without any errors.
When I try to run this code, MT4 does nothing. no indicator displayed...
Any hints?
Thanks alot and bye, AT
MQL4 Code:
#import "sma_rec.dll"
void updateBuffer( double& Rates[], double& buffer[], int bars, int indicator_counted, int ma_period, double& internal_calcs[2] );
#import
//sma_rec.mqh file end
//sma_rec.mq4 file begin
#include
#property indicator_chart_window // indicator plotted in main chart window
#property indicator_buffers 1 // one indicator line to be plotted
#property indicator_color1 Red // plot colour is red - change via GUI
//+------------------------------------------------------------------+
// Import and declare the DLL, with its parameters defined
#import "sma_rec.dll"
// history, buffer and internal_calcs are passed by reference, this means the dll
// will receive pointers to the arrays
void updateBuffer(double& Rates[][6], double& buffer[], int bars, int indicator_counted, int period, double& internal_calcs[2] );
#import
extern int ma_period = 10; // default period is 10 - change via GUI
extern int ma_shift = 0; // default is no shift - change via GUI
double buffer[]; // the indicator buffer - the DLL will
// write to this and it will be plotted
double Rates[][6]; // this will later point to the complete
// chart history
double internal_calcs[2]; // this array will hold the values of the
// internal calculations of the DLL and will
// be read from and written to by the DLL.
// The size of the array is set at 2. If
// needs be, the size can be increased to
// accommodate more complicated calculations
// within the DLL.
int init(){
// set up the indicator buffer
SetIndexStyle(0, DRAW_LINE);
SetIndexShift(0, ma_shift);
SetIndexBuffer(0, buffer);
SetIndexLabel(0, "Recursive SMA");
IndicatorDigits(Digits);
}
int start(){
ArrayCopyRates( Rates, NULL, 0 );
updateBuffer( Rates, buffer, Bars, IndicatorCounted(), ma_period, internal_calcs );
//Print(buffer[]);
}
//sma_rec.mq4 file end
[/CODE]
Code in C++
//dllmain.cpp:
#include "stdafx.h"
BOOL APIENTRY DllMain( HMODULE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
break;
}
return TRUE;
}
main function of SMA rec.cpp
[CODE]
#include
#include "stdafx.h"
#include
#define WIN32_LEAN_AND_MEAN
#define MT4_EXPFUNC __declspec(dllexport)
//+------------------------------------------------------------------+
//| MT4 HISTORY DATA STRUCT |
//+------------------------------------------------------------------+
#pragma pack(push,1)
struct RateInfo
{
__int64 ctm;
double open;
double low;
double high;
double close;
unsigned __int64 vol_tick;
// int spread;
// unsigned __int64 vol_real;
};
#pragma pack(pop)
//---
struct MqlStr
{
int len;
char *string;
};
static int CompareMqlStr(const void *left,const void *right);
//+------------------------------------------------------------------+
//|
EXTERN_C __declspec(dllexport) void __stdcall updateBuffer( RateInfo* Rates, double buffer[],int Bars, int IndicatorCounted, int ma_period, double internal_calcs[2] )
// MT4_EXPFUNC void _stdcall updateBuffer( RateInfo* Rates, double buffer[],int Bars, int IndicatorCounted, int ma_period, double internal_calcs[2] )
{
// check if the DLL is being called for the very first time
if ( IndicatorCounted == 0 )
{
// if so, calculate indicator values from the beginning of the array up to
// "current" bar - firstly for buffer[0] to buffer[ma_period - 1] fill the
// buffer with increasing moving average values up to the desired moving
// average period i.e. the second bar in buffer has value of ma_period = 2;
// the third bar in buffer array has value of ma_period = 3 etc.
buffer[0] = Rates[0].close;
buffer[1] = ( Rates[0].close + Rates[1].close ) / 2.0;
for( int ii = 2 ; ii < ma_period ; ii++ )
{
buffer = ( ( buffer * ii ) / (ii+1) ) + ( Rates.close/(ii+1) );
}
// secondly, after the initial part of the buffer is filled, the rest of the
// buffer is filled using a recursive SMA algorithm. If the SMA were
// calculated by looping over previous bar values there would be ma_period-1
// additions and one division operation per loop of a nested loop. This
// simple recursive algorithm does away with the need for a nested loop
// completely and reduces the number of arithmetic operations to four per
// bar. More importantly, for learning purposes, it will enable code to be
// shown for passing parameters that hold the state of internal calculations
// to and from the DLL.
for( int ii = ma_period ; ii < Bars - 1 ; ii++ )
{
buffer = ( buffer - (Rates.close/ma_period) ) + ( Rates.close/ma_period );
}
// now return the values of the internal calculations to the internal_calcs
// array pending the next call to the DLL
internal_calcs[0] = (Rates.close/ma_period);
// the value // to be used in the next SMA calculation
internal_calcs[1] = Bars - 1; // how many indicator values calculated so far
} // end of ( IndicatorCounted = 0 ) if statement for first call of the DLL.
// Once this piece of the code has been run once, on the initial call to the
// DLL, it will never be run again because the condition IndicatedCounted ==
// 0 will never be true again.
// this next piece of code will be evaluated on the second and all subsequent
// calls to the DLL because the condition IndicatorCounted > 0 will always be
// true after the DLL's initial call. Note that the second part of the
// logical AND, namely (Bars - 1) > internal_calcs[1], ensures that the code
// will only run when a bar has completely formed and a new bar has opened.
// This is important to ensure that values contained in the internal_calcs
// array are not overwritten by the constantly changing values of the
// currently forming bar. Note that, as above, this is a recursive SMA
// algorithm so there is no loop.
if ( IndicatorCounted > 0 && (Bars - 1) > internal_calcs[1] ) // evaluates to TRUE if there is a new bar
{
buffer = ( buffer - internal_calcs[0] ) + ( Rates.close/ma_period ); // calculate new SMA value
internal_calcs[0] = (Rates.close/ma_period); // update
// internal_calcs with new value for next SMA calc.
internal_calcs[1] = Bars - 1; // update how many indicator values calculated so
// far
} // end of ( IndicatorCounted > 0 && (Bars - 1) > internal_calcs[1]) if
// statement
} // end of main function call
What error do you get displayed in the journal or experts tab?
Hi Mladen!
Thanks for answer!
None! That's a problem... :-/
Indicator window is opened, but no indi is displayed...
Thanks for help/ideas and bye, AT
Hi Mladen!
When I try to get the value of the buffer[0] the value is something like Buffer: 2147483647
So I think this is not right... There should be a value something like: 1,23584
as I made a test and set: buffer = Rates[10].close;
Any ideas?
Thanks a lot and bye, AT