Create Expert Advisor (EA)

PC Create Expert Advisor (EA)

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On MetaTrader4 (MT4) / MetaTrader5 (MT5), you use a programming tool called MetaEditor and a dedicated language called MQL4 or MQL5 to create an Expert Advisor (EA).

Here we will look at how to create an Expert Advisor (EA) on MT4/MT5.

Switch between MT4/MT5 tabs to check the steps for each.

Step 1

Click "Tools" in the menu and select "MetaQuotes Language Editor".

Step 2

MetaEditor will be launched. Click the "New" button in the menu.

Step 3

Select "Expert Advisor" and click "Next".

Step 4

Enter the Expert Advisor (EA) name, author, and link to display. Configure the parameters as necessary and click "Next". All fields, except for the indicator name, can be left blank.Other parameters can be adjusted directly in the code, including adding, modifying, or removing them.

The properties settings for an Expert Advisor

Number	Item name	Descriptions
1	Name	Enter the name of the Expert Advisor (EA) that you create.
2	Author	Enter the author of the Expert Advisor (EA).
3	Link	Enter the link to display.

Name and author will be displayed in the settings

The registered name, author, and link information will be displayed on the Expert Advisor (EA) settings window.

Step 5

Set event handlers, which are the functions that are called if certain conditions are met.

Number	Item name	Descriptions
1	OnTrade	OnTrade is a function that handles changes to orders, executions, positions, and trade history when a trade is executed.
2	OnTradeTransaction	OnTradeTransaction is called by the Expert Advisor (EA) when a TradeTranscation event occurs to process the execution result of a trade request.
3	OnTimer	OnTimer is a function that runs at a specified time interval. The interval can be defined or adjusted directly within the code afterwards.
4	OnChartEvent	OnChartEvent is a function that handles events on a chart. It is executed when an event occurs on a chart, such as creating, deleting, moving, or editing an object.
5	OnBookEvent	OnBookEvent is a function that handles the changes in the depth of market data.

Step 6

Set tester event handlers to use.

Number	Item name	Descriptions
1	OnTester	OnTester is a function used for formulas to calculate optimization results in the Strategy Tester.
2	OnTesterInit	OnTesterInit is a function that executes the initialization of the Expert Advisor (EA) when starting optimization in the Strategy Tester.
3	OnTesterPass	OnTesterPass is a function that executes data processing during optimization by the Strategy Tester.
4	OnTesterDeinit	OnTesterDeinit is a function that executes data processing after optimization by the Strategy Tester.

Step 7

Write a program in MQL4.

MQL4 vs MQL5

"MQL4, designed for MT4, and MQL5, used for MT5, share some similarities but are not compatible. Expert Advisors (EAs) created for MT4 cannot be directly used in MT5.While MQL4 is similar to the C programming language, MQL5 is closer to C++, offering greater flexibility and variety."

Step 8

After writing the program, click the "Compile" button in the toolbar.

If a compile error happens

You will get a compile error as shown below if, for example, the syntax of your code is incorrect, or some files are missing.

Missing semicolons and using full-width space are the two most common mistakes made when coding in MQL4. Please check the error message to identify and resolve the issue.

Step 9

After the compilation, the Expert Advisor (EA) created will appear in the Navigator.

Step 10

Close the MetaEditor and go back to MT4. Check that the Expert Advisor (EA) created is in the Navigator on MT4.

Step 1

Click "Tools" in the menu and select "MetaQuotes Language Editor".

Step 2

MetaEditor will be launched. Click the "New" button in the menu.

Step 3

Select "Expert Advisor (template)" or "Expert Advisor (generate)" and click "Next".

"Template" vs "generate"

If you select "Expert Advisor (template)", only the fields configured during the following steps will be filled out, such as parameters and functions. If you select "Expert Adviser (generate)", it will also contain the source code of indicators that come with MT5 by default.

Step 4

"Enter the Expert Advisor (EA) name, author, and link to display. Configure the parameters as necessary and click ""Next"". All fields, except for the indicator name, can be left blank.Other parameters can be adjusted directly in the code, including adding, modifying, or removing them."

Number	Item name	Descriptions
1	Name	Enter the name of the Expert Advisor (EA) that you create.
2	Author	Enter the author of the Expert Advisor (EA).
3	Link	Enter the link of the Expert Advisor (EA) to display.

Name and author will be displayed in settings

The registered name, author, and link information will be displayed on the Expert Advisor (EA) settings window.

Step 5

Set event handlers, which are the functions that are called if certain conditions are met.

Number	Item name	Descriptions
1	OnTrade	OnTrade is a function that handles changes to orders, executions, positions, and trade history when a trade is executed.
2	OnTradeTransaction	OnTradeTransaction is called by the Expert Advisor (EA) when a TradeTranscation event occurs to process the execution result of a trade request.
3	OnTimer	OnTimer is a function that runs at a specified time interval. The interval can be defined or adjusted directly within the code afterwards.
4	OnChartEvent	OnChartEvent is a function that handles events on a chart. It is executed when an event occurs on a chart, such as creating, deleting, moving, or editing an object.
5	OnBookEvent	OnBookEvent is a function that handles the changes in the depth of market data.

Step 6

Set tester event handlers to use.

Number	Item name	Descriptions
1	OnTester	OnTester is a function used for formulas to calculate optimization results in the Strategy Tester.
2	OnTesterlnit	OnTesterInit is a function that executes the initialization of the Expert Advisor (EA) when starting optimization in the Strategy Tester.
3	OnTesterPass	OnTesterPass is a function that executes data processing during optimization by the Strategy Tester.
4	OnTesterDeinit	OnTesterDeinit is a function that executes data processing after optimization by the Strategy Tester.

Step 7

Write a program in MQL5.

MQL4 vs MQL5

MQL4, designed for MT4, and MQL5, used for MT5, share some similarities but are not compatible. Expert Advisors (EAs) created for MT4 cannot be directly used in MT5.While MQL4 is similar to the C programming language, MQL5 is closer to C++, offering greater flexibility and variety.

Step 8

After writing the program, click the "Compile" button in the toolbar.

If a compile error happens

You will get a compile error as shown below if, for example, the syntax of your code is incorrect, or some files are missing.

Missing semicolons and using full-width space are the two most common mistakes made when coding in MQL5. Please check the error message to identify and resolve the issue.