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The new version of the programming language for trading strategy development, MQL [MQL5], provides more powerful and effective features as compared with the previous version [MQL4]. The advantage essentially lies in the object-oriented programming features. This article looks into the possibility of using complex custom data types, such as nodes and lists. It also provides an example of using lists in practical programming in MQL5.
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MetaTarder 4 build 600 features the new structure and location of the client terminal files. Now, MQL4 applications are placed in separate directories according to the program type (Expert Advisors, indicators or scripts). In most cases, the terminal data is now stored in a special data folder separated from the terminal installation location. In this article, we will describe in details how data is transferred, as well as the reasons for introducing the new storage system.
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The new version of the MetaTrader 4 terminal features the updated structure of user data storage. In earlier versions all programs, templates, profiles etc. were stored directly in terminal installation folder. Now all necessary data required for a particular user are stored in a separate directory called data folder. Read the article to find answers to frequently asked questions.
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- Upgrade to New MetaTrader 4
- Data Copied During the Upgrade
- What Is the Data Folder
- What Is the Installation Folder
- General Mode of Terminal Start
- Portable Mode
- How to run old EX4
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To avoid critical completion of programs, the previous version compiler handled many errors in the runtime environment. For example, division by zero or array out of range are critical errors and usually lead to program crash. The new compiler can detect actual or potential sources of errors and improve code quality. In this article, we discuss possible errors that can be detected during compilation of old programs and see how to fix them.
In this article, we discuss possible errors that can be detected during compilation of old programs and ways to fix them.
- Compilation Errors
- 1.1. Identifier coincides with a reserved word
- 1.2. Special characters in the names of variables and functions
- 1.3. Errors using the switch operator
- 1.4. Function return values
- 1.5. Arrays in function arguments
- Runtime Errors
- 2.1. Array out of range
- 2.2. Zero divide
- 2.3. Use of 0 instead of NULL for the current character
- 2.4. Unicode format strings and their use in a DLL
- 2.5. File sharing
- 2.6. Datetime conversion
- Compiler Warnings
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MetaTrader 5 Platform Update Build 930: Books in MetaTrader Market
MetaTrader 5 platform update is to be released on Friday, April 11, 2014. It will contain the following changes:
Market: Another new product category has been added to MetaTrader AppStore following trading and financial magazines - Books. Now, you can purchase the works of well-known traders and analysts along with trading robots and indicators. The range of books is increasing daily.
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Just like MetaTrader 5 applications, books can be purchased at MQL5.community Market as well as directly via MetaTrader 5 terminal. All books are accompanied by descriptions and screenshots:
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Many developers consider using databases in their projects for data storage purposes and yet they remain hesitant about this, knowing how much extra time the SQL server installation may require. And whereas it may not be so difficult for programmers (if a database management system (DBMS) has already been installed for other purposes), it will certainly be an issue for a common user who might eventually be discouraged to install the software altogether.
So many developers choose not to deal with DBMS realizing that solutions they are currently working on will be used by very few people. As a result, they turn to working with files (often having to deal with more than one file, given the variety of data used): CSV, less often XML or JSON, or binary data files with strict structure size, etc.
However, it turns out there is a great alternative to SQL server! And you do not even need to install additional software as everything is done locally in your project, while still allowing you to use the full power of SQL. We are talking about SQLite.
The purpose of this article is to quickly get you started with SQLite. I will therefore not go into subtleties and all imaginable parameter sets and function flags but instead will create a light connection wrapper to execute SQL commands and will demonstrate its use.
To proceed with the article, you need to:
- Be in a good mood ;)
- Extract the archive files attached to the article to the MetaTrader 5 client terminal folder
- Install any convenient SQLite Viewer (e.g. SQLiteStudio)
- Add the official documentation on SQLite http://www.sqlite.org to Favorites
Contents
1. SQLite Principles
2. SQLite3 API
2.1. Opening and Closing a Database
2.2. Execution of SQL Queries
2.3. Getting Data from Tables
2.4. Writing Parameter Data with Binding
2.5. Transactions / Multirow Inserts (Example of Creating the Deal Table of a Trading Account)
3. Compiling 64-Bit Version (sqlite3_64.dll)
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Two years ago in "The Last Crusade" we reviewed quite an interesting yet currently not widely used method for displaying market information - point and figure charts. Now I suggest you try to write a trading robot based on the patterns detected on the point and figure chart.
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From August 1, 2014, MetaTrader 4 desktop terminals older than build 600 will no longer be supported. However, many traders still work with outdated versions and are unaware of the updated platform's features. We have put a lot of effort into development and would like to move on with traders and abandon the older builds. In this article, we will describe the advantages of the new MetaTrader 4.
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The article describes an example of Renko charting and its implementation in MQL5 as an indicator. Modifications of this indicator distinguish it from a classic chart. It can be constructed both in the indicator window and on the main chart. Moreover, there is the ZigZag indicator. You can find a few examples of the chart implementation.
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Algorithmic trading becomes more popular and needed, which naturally led to a demand for exotic algorithms and unusual tasks. To some extent, such complex applications are available in the Code Base or in the Market. Although traders have simple access to those apps in a couple of clicks, these apps may not satisfy all needs in full. In this case, traders look for developers who can write a desired application in the MQL5 Freelance section and assign an order.
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