Meta Trader

MetaQuotes Language 4 (MQL4) is a new built-in language forprogramming of trading strategies. This language allows to createyour own Expert Advisors that make trading management automated andare perfectly suitable for implementing of one's own tradestrategies. Besides, one can use MQL4 for creation of one's ownCustom Indicators, Scripts, and Libraries.

A large amount of functions necessary for analysis of thecurrent and previously income quotes, as well as basic arithmeticand logic operations are included in MQL4 structure. There are alsobasic indicators built in and commands of order placement andcontrol.

The MetaEditor 4 (text editor) that highlights differentconstructions of MQL4 language is used for writing the programcode. It helps users to orientate themselves in the expert systemtext quite easily. We use MetaQuotes Language Dictionary as a HelpSystem for MQL4 language. An abridged guide contains functionsdivided into categories, operations, reserved words, and otherlanguage constructions and allows finding the description of everyelement we use.

Programs written in MetaQuotes Language 4 have differentfeatures and purposes:

• Expert Advisor is a mechanical trading system(MTS) linked up to a certain chart. An Advisor starts to run withevery incoming tick for a given symbol. The Advisor will not belaunched for a new, tick if it is processing the previous one atthis moment (i.e., the Advisor has not completed its operationyet). The Advisor can both inform you about a possibility to tradeand trade at an account automatically sending orders directly tothe trade server. Like most trading systems, the terminal supportstesting strategies on history data with displaying tradingin-and-out points in the chart.
  Experts are stored in terminal_directory\experts.

• Custom Indicator is a technical indicatorwritten independently in addition to those already integrated intothe client terminal. Like built-in indicators, they cannot tradeautomatically and are intended for implementing of analyticalfunctions only.
  Custom Indicators are stored interminal_directory\experts\indicators.

• Script is a program intended for a singleexecution of some actions. Unlike Expert Advisors, Scripts are notrun tickwise, but on request.
  Scripts are stored interminal_dictionary\experts\scripts.

• Library is a set of custom functions containingprograms most frequently used. Libraries cannot start execution byitself.
  Libraries are recommended to be stored interminal_directory\experts\libraries.

• Included file is a source text of the mostfrequently used blocks of custom programs. Such files can beincluded into the source texts of experts, scripts, customindicators, and libraries at the compiling stage. The use ofincluded files is more preferable than the use of libraries becauseof additional burden occurring at calling library functions.
  Included files are recommended to be stored interminal_directory\experts\include