Forex MQL4 EA Properties code 2

External variable or Extern Variable MQL4

From Last Chapter

Extern ones also determine the input parameters of an mql4 EA

They are available from the Properties window

Extern variables can be modified in the Properties window and MQL4 Program

This chapter we would talk about how to coding EA properties

Learn to know Moving Average Indicators

Learn to know Moving Average Functions

Function Name
double iMA
Function Parameter
Function Value	Function Value Name	Function Meaning
symbol	NULL
ENUM_TIMEFRAMES
0	PERIOD_CURRENT
1	PERIOD_M1
5	PERIOD_M5
15	PERIOD_M15
30	PERIOD_M30
60	PERIOD_H1
240	PERIOD_H4
1440	PERIOD_D1
10080	PERIOD_W1
43200	PERIOD_MN1
ma_period	Averaging period for calculation
MA shift	Indicators line offset relate to the chart by timeframe
ENUM_MA_METHOD
0	MODE_SMA
1	MODE_EMA
2	MODE_SMMA
3	MODE_LWMA
ENUM_APPLIED_PRICE
applied_price 0	PRICE_CLOSE	Close price
applied_price 1	PRICE_OPEN	Open price
applied_price 2	PRICE_HIGH	The maximum price for the period
applied_price 3	PRICE_LOW	The minimum price for the period
applied_price 4	PRICE_MEDIAN	Median price, (high + low)/2
applied_price 5	PRICE_TYPICAL	Typical price, (high + low + close)/3
applied_price 6	PRICE_WEIGHTED	Weighted close price, (high + low + close + close)/4
shift		Current candle is 0 (candle 1-N is count back from current candle)

iMA Function Moving Average from MetaQuotes Example

iMA Function Moving Average in MetaQuotes EA or Expert Advisor Examples have 2 lines use iMA function 

that's

ma=iMA(NULL,0,MovingPeriod,MovingShift,MODE_SMA,PRICE_CLOSE,0);

This we would learning how to build EA properties for this function

Basic variable Data Type

Every Vaiable should contain and specific data type as below

int (integers)

double (real numbers)

bool (Boolean values, that is logical values)

string (values of string type)

color (values of color type)

datetime (values of date and time)

Extern MQL4 Variable Group

1. Input Value directly (Like input to Edit Box) to the MQL4 EA properties

2. Input Value pass Boolean drop down list to the MQL4 EA properties

3. Input Value pass EA Methode Function

Time to change the properties of MetaQuotes EA or Expert Advisor Examples code

Function from original code

ma=iMA(NULL,0,MovingPeriod,MovingShift,MODE_SMA,PRICE_CLOSE,0);

This we would add 3 lines to select Time Frame, Moving Everage and Apply Price, so add code as below to EA properties 

Input Enum Variable to the Moving Average Function to the MQL4 code

We have 3 enum variable now

TimeFrameUsed

EMA_method1

Applied_Price1

from original iMA function in the code

ma=iMA(NULL,0,MovingPeriod,MovingShift,MODE_SMA,PRICE_CLOSE,0);

Change to

ma=iMA(NULL,TimeFrameUsed,MovingPeriod,MovingShift,EMA_method1,Applied_Price1,0);

Test Run Moving Average EA on youtube