MQL4 (MetaQuotes Language 4)

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### Script Program Start Function Example

Source: https://docs.mql4.com/cn/constants/objectconstants/enum_object/obj_bitmap

Example demonstrating how to retrieve chart data and prepare arrays for use within a script. This snippet focuses on data retrieval.

```mql4
void OnStart()
{
datetime date[]; // array for storing dates of visible bars  
double close[]; // array for storing Close prices  
//--- bitmap file name  
string file="\
Images\
$\\.bmp";  
//--- number of visible bars in the chart window  
int bars=(int)ChartGetInteger(0,CHART_VISIBLE_BARS);
//--- memory allocation  
ArrayResize(date,bars);
ArrayResize(close,bars);
//--- fill the array of dates  
ResetLastError();  
if(CopyTime(Symbol(),Period(),0,bars,date)==-1)
{
Print("Failed to copy time values! Error code = ",GetLastError());
return;
}
//--- fill the array of Close prices  

```

--------------------------------

### OnStart script example for rectangle label

Source: https://docs.mql4.com/constants/objectconstants/enum_object/obj_rectangle_label

Script start function that gets chart dimensions, calculates label coordinates and size, and creates a rectangle label using RectLabelCreate. Uses input variables InpName, InpBackColor, InpBorder, InpCorner, InpColor, InpStyle, InpLineWidth, InpBack, InpSelection, InpHidden, InpZOrder.

```MQL4
void OnStart()
  {
//--- chart window size
   long x_distance;
   long y_distance;
//--- set window size
   if(!ChartGetInteger(0,CHART_WIDTH_IN_PIXELS,0,x_distance))
     {
      Print("Failed to get the chart width! Error code = ",GetLastError());
      return;
     }
   if(!ChartGetInteger(0,CHART_HEIGHT_IN_PIXELS,0,y_distance))
     {
      Print("Failed to get the chart height! Error code = ",GetLastError());
      return;
     }
//--- define rectangle label coordinates
   int x=(int)x_distance/4;
   int y=(int)y_distance/4;
//--- set label size
   int width=(int)x_distance/4;
   int height=(int)y_distance/4;
//--- create a rectangle label
   if(!RectLabelCreate(0,InpName,0,x,y,width,height,InpBackColor,InpBorder,InpCorner,
                       InpColor,InpStyle,InpLineWidth,InpBack,InpSelection,InpHidden,InpZOrder))
     {
      return;
     }
  }
```

--------------------------------

### Example: Get Indicator Subwindow Number (MQL4)

Source: https://docs.mql4.com/chart_operations/chartwindowfind

This example demonstrates how to get the subwindow number of an indicator, handling calls from both indicators and scripts/EAs. It uses the input parameter 'shortname' to identify the indicator.

```mql4
#property script_show_inputs
//--- input parameters
input string shortname="MACD(12,26,9)";
//+------------------------------------------------------------------+
//| Returns number of the chart window with this indicator |
//+------------------------------------------------------------------+
int GetIndicatorSubWindowNumber(long chartID=0,string short_name="")
{
int window=-1;
//---
if((ENUM_PROGRAM_TYPE)MQLInfoInteger(MQL_PROGRAM_TYPE)==PROGRAM_INDICATOR)
{
//--- the function is called from the indicator, name is not required
window=ChartWindowFind();
}
else
{
//--- the function is called from an Expert Advisor or script
window=ChartWindowFind(0,short_name);
if(window==-1) Print(__FUNCTION__+"(): Error = ",GetLastError());
}
//---
return(window);
}
//+------------------------------------------------------------------+
//| Script program start function |
//+------------------------------------------------------------------+
void OnStart()
{
//---
int window=GetIndicatorSubWindowNumber(0,shortname);
if(window!=-1)
Print("Indicator "+shortname+" is in the window #"+(string)window);
else
Print("Indicator "+shortname+" is not found. window = "+(string)window);
}
```

--------------------------------

### Include examples

Source: https://docs.mql4.com/basis/preprosessor/include

Examples of including WinUser32.mqh from the standard directory and mylib.mqh from the current directory.

```mql4
#include <WinUser32.mqh>  
#include "mylib.mqh"  
```

--------------------------------

### TimeDayOfWeek Example

Source: https://docs.mql4.com/dateandtime/timedayofweek

Example usage of TimeDayOfWeek, demonstrating how to get the day of week for a specific date.

```mql4
int weekday=TimeDayOfWeek(D'2004.11.2');  
// day is 2 - Tuesday
```

--------------------------------

### OnStart Function Example

Source: https://docs.mql4.com/constants/objectconstants/enum_object/obj_arrow_stop

The main entry point for the script. It handles input parameters, creates, moves, changes anchor, and deletes a stop arrow object, with redraws and delays in between.

```mql4
void OnStart()  
{
//--- check correctness of the input parameters  
if(InpDate<0 || InpDate>100 || InpPrice<0 || InpPrice>100)  
{
Print("Error! Incorrect values of input parameters!");  
return;  
}
//--- number of visible bars in the chart window  
int bars=(int)ChartGetInteger(0,CHART_VISIBLE_BARS);  
//--- price array size  
int accuracy=1000;  
//--- arrays for storing the date and price values to be used  
//--- for setting and changing sign anchor point coordinates  
datetime date[];  
double price[];  
//--- memory allocation  
ArrayResize(date,bars);  
ArrayResize(price,accuracy);  
//--- fill the array of dates  
ResetLastError();  
if(CopyTime(Symbol(),Period(),0,bars,date)==-1)  
{
Print("Failed to copy time values! Error code = ",GetLastError());  
return;  
}
//--- fill the array of prices  
//--- find the highest and lowest values of the chart  
double max_price=ChartGetDouble(0,CHART_PRICE_MAX);  
double min_price=ChartGetDouble(0,CHART_PRICE_MIN);  
//--- define a change step of a price and fill the array  
double step=(max_price-min_price)/accuracy;  
for(int i=0;i<accuracy;i++)  
price[i]=min_price+i*step;  
//--- define points for drawing the sign  
int d=InpDate*(bars-1)/100;  
int p=InpPrice*(accuracy-1)/100;  
//--- create Stop sign on the chart  
if(!ArrowStopCreate(0,InpName,0,date[d],price[p],InpAnchor,InpColor,  
InpStyle,InpWidth,InpBack,InpSelection,InpHidden,InpZOrder))  
{
return;  
}
//--- redraw the chart and wait for 1 second  
ChartRedraw();  
Sleep(1000);  
//--- now, move the anchor point and change its position relative to the sign  
//--- loop counter  
int h_steps=bars*2/5;  
//--- move the anchor point  
for(int i=0;i<h_steps;i++)  
{
//--- use the following value  
if(d<bars-1)  
d+=1;  
//--- move the point  
if(!ArrowStopMove(0,InpName,date[d],price[p]))  
return;  
//--- check if the script's operation has been forcefully disabled  
if(IsStopped())  
return;  
//--- redraw the chart  
ChartRedraw();  
// 0.025 seconds of delay  
Sleep(25);  
}
//--- change anchor point location relative to the sign  
ArrowStopAnchorChange(0,InpName,ANCHOR_TOP);  
//--- redraw the chart  
ChartRedraw();  
//--- loop counter  
h_steps=bars*2/5;  
//--- move the anchor point  
for(int i=0;i<h_steps;i++)  
{
//--- use the following value  
if(d<bars-1)  
d+=1;  
//--- move the point  
if(!ArrowStopMove(0,InpName,date[d],price[p]))  
return;  
//--- check if the script's operation has been forcefully disabled  
if(IsStopped())  
return;  
//--- redraw the chart  
ChartRedraw();  
// 0.025 seconds of delay  
Sleep(25);  
}
//--- 1 second of delay  
Sleep(1000);  
//--- delete the sign from the chart  
ArrowStopDelete(0,InpName);  
ChartRedraw();  
//--- 1 second of delay  
Sleep(1000);  
//---  
}

```

--------------------------------

### Complete script example applying a template from \MQL4\Files

Source: https://docs.mql4.com/chart_operations/chartapplytemplate

A full OnStart() script that checks if 'my_template.tpl' exists in the \MQL4\Files folder, applies it using ChartApplyTemplate(), and prints success or error messages with GetLastError().

```mql4
//+------------------------------------------------------------------+  
//| Script program start function |  
//+------------------------------------------------------------------+  
void OnStart()  
{  
//--- example of applying template, located in \MQL4\Files  
if(FileIsExist("my_template.tpl"))  
{  
Print("The file my_template.tpl found in \Files'");  
//--- apply template  
if(ChartApplyTemplate(0,"\\Files\\my_template.tpl"))  
{  
Print("The template 'my_template.tpl' applied successfully");  
}  
else  
Print("Failed to apply 'my_template.tpl', error code ",GetLastError());  
}  
else  
{  
Print("File 'my_template.tpl' not found in "  
+TerminalInfoString(TERMINAL_PATH)+"\\MQL4\\Files");  
}  
}
```

--------------------------------

### TimeDay usage example

Source: https://docs.mql4.com/cn/dateandtime/timeday

Example usage of TimeDay to get the day of month from a specific date.

```mql4
int day=TimeDay(D'2003.12.31');  
// day is 31  
```

--------------------------------

### OnStart Function - Button Animation Example

Source: https://docs.mql4.com/constants/objectconstants/enum_object/obj_button

This example demonstrates the lifecycle of a button, from creation to dynamic resizing and eventual deletion, within the OnStart function of an MQL4 script. It includes visual feedback through chart redrawing.

```mql4
void OnStart()
{
//--- chart window size
long x_distance;
long y_distance;
//--- set window size
if(!ChartGetInteger(0,CHART_WIDTH_IN_PIXELS,0,x_distance))
{
Print("Failed to get the chart width! Error code = ",GetLastError());
return;
}
if(!ChartGetInteger(0,CHART_HEIGHT_IN_PIXELS,0,y_distance))
{
Print("Failed to get the chart height! Error code = ",GetLastError());
return;
}
//--- define the step for changing the button size
int x_step=(int)x_distance/32;
int y_step=(int)y_distance/32;
//--- set the button coordinates and its size
int x=(int)x_distance/32;
int y=(int)y_distance/32;
int x_size=(int)x_distance*15/16;
int y_size=(int)y_distance*15/16;
//--- create the button
if(!ButtonCreate(0,InpName,0,x,y,x_size,y_size,InpCorner,"Press",InpFont,InpFontSize,
InpColor,InpBackColor,InpBorderColor,InpState,InpBack,InpSelection,InpHidden,InpZOrder))
{
return;
}
//--- redraw the chart
ChartRedraw();
//--- reduce the button in the loop
int i=0;
while(i<13)
{
//--- half a second of delay
Sleep(500);
//--- switch the button to the pressed state
ObjectSetInteger(0,InpName,OBJPROP_STATE,true);
//--- redraw the chart and wait for 0.2 second
ChartRedraw();
Sleep(200);
//--- redefine coordinates and button size
x+=x_step;
y+=y_step;
x_size-=x_step*2;
y_size-=y_step*2;
//--- reduce the button
ButtonMove(0,InpName,x,y);
ButtonChangeSize(0,InpName,x_size,y_size);
//--- bring the button back to the released state
ObjectSetInteger(0,InpName,OBJPROP_STATE,false);
//--- redraw the chart
ChartRedraw();
//--- check if the script's operation has been forcefully disabled
if(IsStopped())
return;
//--- increase the loop counter
i++;
}
//--- half a second of delay
Sleep(500);
//--- delete the button
ButtonDelete(0,InpName);
ChartRedraw();
//--- wait for 1 second
Sleep(1000);
//---  
}
```

--------------------------------

### MQL4 IndicatorCounted Example Usage

Source: https://docs.mql4.com/customind/indicatorcounted

This example demonstrates how to use IndicatorCounted() within the start() function of a custom indicator to optimize calculations. It ensures that only necessary bars are recalculated.

```mql4
int start()
{
int limit;
int counted_bars=IndicatorCounted();
//---- check for possible errors
if(counted_bars<0) return(-1);
//---- the last counted bar will be recounted
if(counted_bars>0) counted_bars--;
limit=Bars-counted_bars;
//---- main loop
for(int i=0; i<limit; i++)
{
//---- ma_shift set to 0 because SetIndexShift called abowe
ExtBlueBuffer[i]=iMA(NULL,0,JawsPeriod,0,MODE_SMMA,PRICE_MEDIAN,i);
ExtRedBuffer[i]=iMA(NULL,0,TeethPeriod,0,MODE_SMMA,PRICE_MEDIAN,i);
ExtLimeBuffer[i]=iMA(NULL,0,LipsPeriod,0,MODE_SMMA,PRICE_MEDIAN,i);
}
//---- done
return(0);
}
```

--------------------------------

### FileOpen Example

Source: https://docs.mql4.com/cn/files/fileopen

Example script demonstrating correct and incorrect ways to open files in MQL4, including handling of file sandbox and subfolders.

```mql4
//+------------------------------------------------------------------+  
//| Script program start function |  
//+------------------------------------------------------------------+  
void OnStart()  
{  
//--- incorrect file opening method  
string terminal_data_path=TerminalInfoString(TERMINAL_DATA_PATH);  
string filename=terminal_data_path+"\\\MQL4\\\Files\\\"+"fractals.csv";  
int filehandle=FileOpen(filename,FILE_WRITE|FILE_CSV);  
if(filehandle<0)  
{  
Print("Failed to open the file by the absolute path ");  
Print("Error code ",GetLastError());  
}  
//--- correct way of working in the "file sandbox"  
ResetLastError();  
filehandle=FileOpen("fractals.csv",FILE_WRITE|FILE_CSV);  
if(filehandle!=INVALID_HANDLE)  
{  
FileWrite(filehandle,TimeCurrent(),Symbol(), EnumToString(ENUM_TIMEFRAMES(_Period)));  
FileClose(filehandle);  
Print("FileOpen OK");  
}  
else Print("Operation FileOpen failed, error ",GetLastError());  
//--- another example with the creation of an enclosed directory in MQL4\Files\  
string subfolder="Research";  
filehandle=FileOpen(subfolder+"\\\fractals.txt",FILE_WRITE|FILE_CSV);  
if(filehandle!=INVALID_HANDLE)  
{  
FileWrite(filehandle,TimeCurrent(),Symbol(), EnumToString(ENUM_TIMEFRAMES(_Period)));  
FileClose(filehandle);  
Print("The file most be created in the folder "+terminal_data_path+"\\"+subfolder);  
}  
else Print("File open failed, error ",GetLastError());  
}  
```

--------------------------------

### Get Executing Program Name - MQL4

Source: https://docs.mql4.com/chart_operations/windowexpertname

Use WindowExpertName to retrieve the name of the currently running MQL4 program. This example shows how to get the name and then delete all global variables associated with it.

```mql4
string name=WindowExpertName();
GlobalVariablesDeleteAll(name);
```

--------------------------------

### OnStart script for Fibonacci Fan setup

Source: https://docs.mql4.com/constants/objectconstants/enum_object/obj_fibofan

Script entry point that validates input parameters (must be between 0 and 100) and prepares date and price arrays for Fibonacci Fan anchor points. Uses ChartGetInteger and CopyTime; prints an error and returns on invalid input or copy failure.

```MQL4
void OnStart()  
{  
//--- check correctness of the input parameters  
if(InpDate1<0 || InpDate1>100 || InpPrice1<0 || InpPrice1>100 ||   
InpDate2<0 || InpDate2>100 || InpPrice2<0 || InpPrice2>100)  
{  
Print("Error! Incorrect values of input parameters!");  
return;  
}  
//--- number of visible bars in the chart window  
int bars=(int)ChartGetInteger(0,CHART_VISIBLE_BARS);  
//--- price array size  
int accuracy=1000;  
//--- arrays for storing the date and price values to be used  
//--- for setting and changing the coordinates of Fibonacci Fan anchor points  
datetime date[];  
double price[];  
//--- memory allocation  
ArrayResize(date,bars);  
ArrayResize(price,accuracy);  
//--- fill the array of dates  
ResetLastError();  
if(CopyTime(Symbol(),Period(),0,bars,date)==-1)  
{  
Print("Failed to copy time values! Error code = ",GetLastError());  
return;  
}
```

--------------------------------

### Complete MQL4 script demonstrating object pointers and passing by reference

Source: https://docs.mql4.com/cn/basis/types/object_pointers

Defines class Foo with constructors, a static counter, and a Setup method. The OnStart function creates objects, pointers, arrays of objects, and arrays of pointers, passes them to functions that accept references, and deletes dynamically created objects. Functions PrintObject, PrintObjectsArray, and PrintPointersArray show how to pass objects, arrays of objects, and arrays of pointers by reference.

```mql4
class Foo  
{  
public:  
string m_name;  
int m_id;  
static int s_counter;  
//--- constructors and desctructors  
Foo(void){Setup("noname");};  
Foo(string name){Setup(name);};  
~Foo(void){};  
//--- initializes object of type Foo  
void Setup(string name)  
{  
m_name=name;  
s_counter++;  
m_id=s_counter;  
}  
};  
int Foo::s_counter=0;  
//+------------------------------------------------------------------+  
//| Script program start function |  
//+------------------------------------------------------------------+  
void OnStart()  
{  
//--- declare an object as variable with its automatic creation  
Foo foo1;  
//--- variant of passing an object by reference  
PrintObject(foo1);  
  
//--- declare a pointer to an object and create it using the 'new' operator  
Foo *foo2=new Foo("foo2");  
//--- variant of passing a pointer to an object by reference  
PrintObject(foo2); // pointer to an object is converted automatically by compiler  
  
//--- declare an array of objects of type Foo  
Foo foo_objects[5];  
//--- variant of passing an array of objects  
PrintObjectsArray(foo_objects); // separate function for passing an array of objects  
  
//--- declare an array of pointers to objects of type Foo  
Foo *foo_pointers[5];  
for(int i=0;i<5;i++)  
{  
foo_pointers[i]=new Foo("foo_pointer");  
}  
//--- variant of passing an array of pointers  
PrintPointersArray(foo_pointers); // separate function for passing an array of pointers  
  
//--- it is obligatory to delete objects created as pointers before termination  
delete(foo2);  
//--- delete array of pointers  
int size=ArraySize(foo_pointers);  
for(int i=0;i<5;i++)  
delete(foo_pointers[i]);  
//---   
}  
//+------------------------------------------------------------------+  
//| Objects are always passed by reference |  
//+------------------------------------------------------------------+  
void PrintObject(Foo &object)  
{  
Print(__FUNCTION__,": ",object.m_id," Object name=",object.m_name);  
}  
//+------------------------------------------------------------------+  
//| Passing an array of objects |  
//+------------------------------------------------------------------+  
void PrintObjectsArray(Foo &objects[])  
{  
int size=ArraySize(objects);  
for(int i=0;i<size;i++)  
{  
PrintObject(objects[i]);  
}  
}  
//+------------------------------------------------------------------+  
//| Passing an array of pointers to object |  
//+------------------------------------------------------------------+  
void PrintPointersArray(Foo* &objects[])  
{  
int size=ArraySize(objects);  
for(int i=0;i<size;i++)  
{  
PrintObject(objects[i]);  
}  
}  
//+------------------------------------------------------------------+
```

--------------------------------

### Hexadecimal integer literals

Source: https://docs.mql4.com/cn/basis/types/integer/integertypes

Examples of hexadecimal integer literals in MQL4, starting with 0x or 0X.

```mql4
0x0A, 0x12, 0X12, 0x2f, 0xA3, 0Xa3, 0X7C7  
```

--------------------------------

### CopyRates overload: by start position and count

Source: https://docs.mql4.com/cn/series/copyrates

First variant of CopyRates, copying a specified number of elements starting from a given position. Use start_pos=0 and count=1 to get the current uncompleted bar.

```MQL4
int CopyRates(  
string symbol_name, // symbol name  
ENUM_TIMEFRAMES timeframe, // period  
int start_pos, // start position  
int count, // data count to copy  
MqlRates rates_array[] // target array to copy  
);
```

--------------------------------

### Example: Using FileSize to move files by size

Source: https://docs.mql4.com/files/filesize

Example script that uses FileSize to determine file size and move files to folders based on a threshold. It uses FileFindFirst, FileOpen, FileMove, and FileFindClose. Requires input parameters for threshold size and folder names.

```mql4
//--- show the window of input parameters when launching the script  
#property script_show_inputs  
//--- input parameters  
input ulong InpThresholdSize=20; // file threshold size in kilobytes  
input string InpBigFolderName="big"; // folder for large files  
input string InpSmallFolderName="small"; // folder for small files  
//+------------------------------------------------------------------+  
//| Script program start function |  
//+------------------------------------------------------------------+  
void OnStart()  
{  
string file_name; // variable for storing file names  
string filter="*.csv"; // filter for searching the files  
ulong file_size=0; // file size in bytes  
int size=0; // number of files  
//--- print the path to the file we are going to work with  
PrintFormat("Working in %s\\Files\\ folder",TerminalInfoString(TERMINAL_COMMONDATA_PATH));  
//--- receive the search handle in common folder's root of all terminals  
long search_handle=FileFindFirst(filter,file_name,FILE_COMMON);  
//--- check if FileFindFirst() has been executed successfully  
if(search_handle!=INVALID_HANDLE)  
{  
//--- move files in the loop according to their size  
do  
{  
//--- open the file  
ResetLastError();  
int file_handle=FileOpen(file_name,FILE_READ|FILE_CSV|FILE_COMMON);  
if(file_handle!=INVALID_HANDLE)  
{  
//--- receive the file size  
file_size=FileSize(file_handle);  
//--- close the file  
FileClose(file_handle);  
}  
else  
{  
PrintFormat("Failed to open %s file, Error code = %d",file_name,GetLastError());  
continue;  
}  
//--- print the file size  
PrintFormat("Size of %s file is equal to %d bytes",file_name,file_size);  
//--- define the path for moving the file  
string path;  
if(file_size>InpThresholdSize*1024)  
path=InpBigFolderName+"//"+file_name;  
else  
path=InpSmallFolderName+"//"+file_name;  
//--- move the file  
ResetLastError();  
if(FileMove(file_name,FILE_COMMON,path,FILE_REWRITE|FILE_COMMON))  
PrintFormat("%s file is moved",file_name);  
else  
PrintFormat("Error, code = %d",GetLastError());  
}  
while(FileFindNext(search_handle,file_name));  
//--- close the search handle  
FileFindClose(search_handle);  
}  
else  
Print("Files not found!");  
}
```

--------------------------------

### OnStart Event Handler for Scripts

Source: https://docs.mql4.com/basis/function/events

The OnStart() function is the entry point for MQL4 scripts. It must be of void type and take no parameters. It is automatically generated when a script is run.

```mql4
void OnStart();
```

--------------------------------

### Get Chart Subwindow Index with ChartWindowOnDropped

Source: https://docs.mql4.com/chart_operations/chartwindowondropped

Use ChartWindowOnDropped to get the index of the chart subwindow where the script or Expert Advisor is dropped. This example also retrieves the total number of windows on the chart and prints the information.

```mql4
int myWindow=ChartWindowOnDropped();
int windowsTotal=ChartGetInteger(0,CHART_WINDOWS_TOTAL);
Print("Script is running on the window #"+myWindow+
". Total windows on the chart "+ChartSymbol()+ ":",windowsTotal);
```

--------------------------------

### MQL5 Script Lifecycle Example

Source: https://docs.mql4.com/runtime/running

Demonstrates the initialization and deinitialization functions of an MQL5 script, including a global class instance with a constructor and destructor. This helps visualize the script's loading and unloading process.

```mql5
#property copyright "2014, MetaQuotes Software Corp."
#property link "https://www.mql5.com"
#property version "1.00"

class CTestClass
{
public: 
CTestClass() { Print("CTestClass constructor"); }
~CTestClass() { Print("CTestClass destructor"); }
};
CTestClass global;
//+------------------------------------------------------------------+
//| Script program initialization function |
//+------------------------------------------------------------------+
void OnInit()
{
Print(__FUNCTION__);
}
//+------------------------------------------------------------------+
//| Script program deinitialization function |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
{
Print(__FUNCTION__," reason=",reason);
}
//+------------------------------------------------------------------+
//| Script program start function |
//+------------------------------------------------------------------+
void OnStart()
{
//---
Print(__FUNCTION__);
}
```

--------------------------------

### IndicatorShortName example in init()

Source: https://docs.mql4.com/customind/indicatorshortname

Sets the short name for a custom indicator, used in the DataWindow and chart subwindow. The example shows the function call within an init() function, along with buffer setup and drawing settings.

```mql4
int init()  
{  
//---- 2 additional buffers are used for counting.  
IndicatorBuffers(3);  
//---- drawing settings  
SetIndexStyle(0,DRAW_HISTOGRAM,STYLE_SOLID,3);  
SetIndexDrawBegin(0,SignalSMA);  
IndicatorDigits(MarketInfo(Symbol(),MODE_DIGITS)+2);  
//---- 3 indicator buffers mapping  
SetIndexBuffer(0,ind_buffer1);  
SetIndexBuffer(1,ind_buffer2);  
SetIndexBuffer(2,ind_buffer3);  
//---- name for DataWindow and indicator subwindow label  
IndicatorShortName("OsMA("+FastEMA+","+SlowEMA+","+SignalSMA+")");  
//---- initialization done  
return(0);  
}  
```

--------------------------------

### Example: Get Low for specified bar index

Source: https://docs.mql4.com/cn/series/copyhigh

Example showing how to retrieve the Low value for a specified bar index using CopyLow. It sets the array as a series, copies all available bars, and returns the value if the index is valid. The example is provided for CopyHigh but uses CopyLow; the same pattern applies to CopyHigh.

```cpp
#property copyright "2009, MetaQuotes Software Corp."  
#property link "https://www.mql5.com"  
#property version "1.00"  
  
#property description "An example for output of the High[i] and Low[i]"  
#property description "for a random chosen bars"  
  
double High[],Low[];  
//+------------------------------------------------------------------+  
//| Get Low for specified bar index |  
//+------------------------------------------------------------------+  
double iLow(string symbol,ENUM_TIMEFRAMES timeframe,int index)  
{  
double low=0;  
ArraySetAsSeries(Low,true);  
int copied=CopyLow(symbol,timeframe,0,Bars(symbol,timeframe),Low);  
if(copied>0 && index<copied) low=Low[index];  
return(low);  
}
```

--------------------------------

### Structure Initialization Examples

Source: https://docs.mql4.com/basis/variables/initialization

Demonstrates partial initialization of structures containing arrays and nested structures. The examples show that missing elements are initialized to zero, and the output of Print statements illustrates the resulting values.

```mql4
struct str3  
{  
int low_part;  
int high_part;  
};  
struct str10  
{  
str3 s3;  
double d1[10];  
int i3;  
};  
void OnStart()  
{  
str10 s10_1={{1,0},{1.0,2.1,3.2,4.4,5.3,6.1,7.8,8.7,9.2,10.0},100};  
str10 s10_2={{1,0},{0},100};  
str10 s10_3={{1,0},{1.0}};  
//---  
Print("1. s10_1.d1[5] = ",s10_1.d1[5]);  
Print("2. s10_2.d1[5] = ",s10_2.d1[5]);  
Print("3. s10_3.d1[5] = ",s10_3.d1[5]);  
Print("4. s10_3.d1[0] = ",s10_3.d1[0]);  
}
```

--------------------------------

### Get current minute with TimeMinute

Source: https://docs.mql4.com/cn/dateandtime/timeminute

Example call to TimeMinute using TimeCurrent() to obtain the minute of the current server time.

```MQL4
int m=TimeMinute(TimeCurrent());
```

--------------------------------

### CopyRates usage example in OnStart

Source: https://docs.mql4.com/cn/series/copyrates

Example that copies the latest 100 bars for the current symbol and timeframe, then prints the first 10 bars' open, high, low, close, and tick volume. Uses ArraySetAsSeries to set indexing from present to past.

```MQL4
void OnStart()  
{  
//---  
MqlRates rates[];  
ArraySetAsSeries(rates,true);  
int copied=CopyRates(Symbol(),0,0,100,rates);  
if(copied>0)  
{  
Print("Bars copied: "+copied);  
string format="open = %G, high = %G, low = %G, close = %G, volume = %d";  
string out;  
int size=fmin(copied,10);  
for(int i=0;i<size;i++)  
{  
out=i+":"+TimeToString(rates[i].time);  
out=out+" "+StringFormat(format,  
rates[i].open,  
rates[i].high,  
rates[i].low,  
rates[i].close,  
rates[i].tick_volume);  
Print(out);  
}  
}  
else Print("Failed to get history data for the symbol ",Symbol());  
}
```

--------------------------------

### Get Chart Double Property Example

Source: https://docs.mql4.com/cn/constants/chartconstants/charts_samples

This snippet shows how to retrieve a double-precision floating-point property of a chart. It includes error handling for when the property cannot be retrieved.

```mql4
if(!ChartGetDouble(chart_ID,CHART_PRICE_MAX,sub_window,result))
{
//--- display the error message in Experts journal
Print(__FUNCTION__+", Error Code = ",GetLastError());
}
//--- return the value of the chart property
return(result);
}
```

--------------------------------

### FileFindClose Example Script

Source: https://docs.mql4.com/files/filefindclose

Complete example script demonstrating the use of FileFindFirst, FileFindNext, and FileFindClose to list files and directories in the local folder.

```cpp
//--- display the window of input parameters when launching the script  
#property script_show_inputs  
//--- filter  
input string InpFilter="*";  
//---+  
//| Script program start function |  
//---+  
void OnStart()  
{  
string file_name;  
int i=1;  
//--- receive search handle in local folder's root  
long search_handle=FileFindFirst(InpFilter,file_name);  
//--- check if FileFindFirst() function executed successfully  
if(search_handle!=INVALID_HANDLE)  
{  
//--- check if the passed strings are file or directory names in the loop  
do  
{  
ResetLastError();  
//--- if this is a file, the function will return true, if it is a directory, the function will generate error 5018  
FileIsExist(file_name);  
PrintFormat("%d : %s name = %s",i,GetLastError()==5018 ? "Directory" : "File",file_name);  
i++;  
}  
while(FileFindNext(search_handle,file_name));  
//--- close search handle  
FileFindClose(search_handle);  
}  
else  
Print("Files not found!");  
}  
```

--------------------------------

### Get Visible Bars Count with WindowBarsPerChart

Source: https://docs.mql4.com/chart_operations/windowbarsperchart

This example demonstrates how to retrieve the number of visible bars on the chart using WindowBarsPerChart and then iterate through them using WindowFirstVisibleBar.

```mql4
// work with visible bars.  
int bars_count=WindowBarsPerChart();  
int bar=WindowFirstVisibleBar();  
for(int i=0; i<bars_count; i++,bar--)  
{
// ...  
}
```

--------------------------------

### TimeYear example: Get year from TimeCurrent()

Source: https://docs.mql4.com/dateandtime/timeyear

Returns the year of the current server time. The result is stored in an integer variable y. The returned year can range from 1970 to 3000.

```MQL4
int y=TimeYear(TimeCurrent());
```

--------------------------------

### OnStart Function

Source: https://docs.mql4.com/basis/function/events

The OnStart() function is the Start event handler, automatically generated only for running scripts. It must be of void type with no parameters.

```APIDOC
## OnStart

### Description
This function is the Start event handler for scripts.

### Signature
```mql4
void OnStart();
```

### Notes
- The `int` return type can also be specified for the OnStart() function.
```

--------------------------------

### Expert Advisor Initialization and Deinitialization Example

Source: https://docs.mql4.com/cn/runtime/running

This MQL5 code demonstrates the basic structure of an Expert Advisor, including OnInit() for initialization and OnDeinit() for deinitialization. It also shows the use of global variables and class constructors/destructors.

```mql5
#property copyright "2009, MetaQuotes Software Corp."
#property link "https://www.mql5.com"
#property version "1.00"

class CTestClass
{
public: 
CTestClass() { Print("CTestClass constructor"); }
~CTestClass() { Print("CTestClass destructor"); }
};
CTestClass global;
//+------------------------------------------------------------------+
//| Expert initialization function |
//+------------------------------------------------------------------+
int OnInit()
{
//---
Print("Initialization");
//---
return(INIT_SUCCEEDED);
}
//+------------------------------------------------------------------+
//| Expert deinitialization function |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
{
//---
Print("Deinitialization with reason",reason);
}
//+------------------------------------------------------------------+
//| Expert tick function |
//+------------------------------------------------------------------+
void OnTick()
{
//---
  
}
//+------------------------------------------------------------------+
```

--------------------------------

### Get terminal path with TerminalInfoString(TERMINAL_PATH)

Source: https://docs.mql4.com/cn/runtime/resources

Shows how to obtain the terminal directory path using TerminalInfoString(TERMINAL_PATH). This path is where the terminal is started from and contains the Sounds folder.

```mql4
//--- Folder, in which terminal data are stored
string terminal_path=TerminalInfoString(TERMINAL_PATH);
```

--------------------------------

### Get Stop Out Level with AccountStopoutLevel()

Source: https://docs.mql4.com/account/accountstopoutlevel

Use this MQL4 function to retrieve the Stop Out level. The example prints the level to the log. The function has no parameters and returns an integer value.

```mql4
int AccountStopoutLevel();
```

```mql4
Print("StopOut level = ", AccountStopoutLevel());
```

--------------------------------

### Script start function for Gann Line creation

Source: https://docs.mql4.com/cn/constants/objectconstants/enum_object/obj_gannline

The OnStart function validates input parameters, retrieves the number of visible bars, and allocates arrays for storing date and price values used to set and change anchor point coordinates.

```MQL4
//+------------------------------------------------------------------+  
//| Script program start function |  
//+------------------------------------------------------------------+  
void OnStart()  
{  
//--- check correctness of the input parameters  
if(InpDate1<0 || InpDate1>100 || InpPrice1<0 || InpPrice1>100 ||   
InpDate2<0 || InpDate2>100)  
{  
Print("Error! Incorrect values of input parameters!");  
return;  
}  
//--- number of visible bars in the chart window  
int bars=(int)ChartGetInteger(0,CHART_VISIBLE_BARS);  
//--- price array size  
int accuracy=1000;  
//--- arrays for storing the date and price values to be used  
//--- for setting and changing line anchor points' coordinates  
datetime date[];  
double price[];  
//--- memory allocation  
ArrayResize(date,bars);
```

--------------------------------

### ArrayFill Example

Source: https://docs.mql4.com/array/arrayfill

Demonstrates filling a dynamic array with ArrayFill() in MQL4.

```cpp
void OnStart()
{
//--- declare dynamic array
int a[];
//--- set size
ArrayResize(a,10);
//--- fill first 5 elements with 123
ArrayFill(a,0,5,123);
//--- fill next 5 elements with 456
ArrayFill(a,5,5,456);
//--- show values
for(int i=0;i<ArraySize(a);i++) printf("a[%d] = %d",i,a[i]);
}
```

--------------------------------

### Get Order Take Profit Value

Source: https://docs.mql4.com/trading/ordertakeprofit

This example demonstrates how to select an order by its position and then retrieve its take profit value. Ensure OrderSelect() is called successfully before using OrderTakeProfit().

```mql4
if(OrderSelect(12, SELECT_BY_POS)==true) 
Print("Order #",OrderTicket()," profit: ", OrderTakeProfit()); 
else 
Print("OrderSelect() returns error - ",GetLastError());
```

--------------------------------

### Variable and Array Initialization Examples

Source: https://docs.mql4.com/basis/variables/initialization

Shows initialization of a simple integer, a string, a one-dimensional double array, a two-dimensional integer array, an array with constant expressions, and a structure initialized to zero. Global and static variables must use constants or constant expressions.

```mql4
int n = 1;  
string s = "hello";  
double f[] = { 0.0, 0.236, 0.382, 0.5, 0.618, 1.0 };  
int a[4][4] = { {1, 1, 1, 1}, {2, 2, 2, 2}, {3, 3, 3, 3}, {4, 4, 4, 4 } };  
//--- from tetris  
int right[4]={WIDTH_IN_PIXELS+VERT_BORDER,WIDTH_IN_PIXELS+VERT_BORDER,  
WIDTH_IN_PIXELS+VERT_BORDER,WIDTH_IN_PIXELS+VERT_BORDER};  
//--- initialization of all fields of the structure with zero values  
MqlTradeRequest request={0};
```

--------------------------------

### MQL4 iMAOnArray Example Usage

Source: https://docs.mql4.com/indicators/imaonarray

Demonstrates how to use iMAOnArray to get current and previous Moving Average values for two different periods and trigger an alert on a crossing event.

```mql4
double macurrent=iMAOnArray(ExtBuffer,0,5,0,MODE_LWMA,0);
double macurrentslow=iMAOnArray(ExtBuffer,0,10,0,MODE_LWMA,0);
double maprev=iMAOnArray(ExtBuffer,0,5,0,MODE_LWMA,1);
double maprevslow=iMAOnArray(ExtBuffer,0,10,0,MODE_LWMA,1);
//----
if(maprev<maprevslow && macurrent>=macurrentslow)
Alert("crossing up");
```

--------------------------------

### MQL4 OnDeinit Function Example

Source: https://docs.mql4.com/constants/namedconstants/uninit

This example demonstrates how to use the `OnDeinit` function in MQL4 to capture and log the reason for program uninitialization. It shows two methods for obtaining the reason code: directly via the `reason` parameter and indirectly by calling a helper function `getUninitReasonText` with `_UninitReason`.

```mql4
//+------------------------------------------------------------------+
//| Expert deinitialization function |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
{
//--- The first way to get the uninitialization reason code
Print(__FUNCTION__,"_Uninitalization reason code = ",reason);
//--- The second way to get the uninitialization reason code
Print(__FUNCTION__,"_UninitReason = ",getUninitReasonText(_UninitReason));
}
```

--------------------------------

### Get X and Y coordinates of drop point

Source: https://docs.mql4.com/chart_operations/chartxondropped

Example from the ChartXOnDropped reference. Calls ChartXOnDropped() and ChartYOnDropped() to obtain the drop coordinates and prints them. X axis direction is from left to right.

```mql4
int X=ChartXOnDropped();  
int Y=ChartYOnDropped();  
Print("(X,Y) = ("+X+","+Y+")");  
```
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