1
Keyboard Shortcut (F4)
Press F4 at any time while the MetaTrader 4 or MetaTrader 5 terminal is active. Pressing F4 again switches back to MetaTrader.
MetaQuotes development environment
MetaEditor: The Complete Guide to MT4 & MT5 Code Development
MetaEditor is the built-in integrated development environment (IDE) and compiler for MetaTrader 4 and MetaTrader 5. It is used to write, edit, compile, debug, and profile MQL4 and MQL5 programs, including Expert Advisors, custom indicators, scripts, and libraries.
Also covering MetaEditor 4, MetaEditor 5, and MQL code compilation workflows.
Getting started
How to Open MetaEditor in MT5 and MT4
MetaEditor is packaged directly inside MetaTrader installations. You can launch the editor using any of the following five methods.
2
Top Menu Navigation
In the MetaTrader main menu, click Tools and select "MetaQuotes Language Editor".
3
Standard Toolbar Icon
Click the IDE icon (resembling a notebook with a pencil and yellow IDE emblem) located on the main toolbar.
4
Navigator Context Menu
Expand Expert Advisors or Indicators in the Navigator pane, right-click any custom program, and click "Modify" to open its source in MetaEditor.
5
Direct Executable Launch
Launch metaeditor64.exe (for MT5) or metaeditor.exe (for MT4) directly from the terminal installation folder or command line.
Version comparison
MetaEditor 4 vs MetaEditor 5
While both editors share a familiar interface, MetaEditor 5 introduces a 64-bit compilation pipeline, native MQL5 object-oriented programming support, and runtime profiling.
| Feature | MetaEditor 4 (MT4) | MetaEditor 5 (MT5) |
|---|---|---|
| Architecture & Performance | 32-bit single-process IDE | 64-bit multi-threaded IDE with fast compilation |
| Primary Language | MQL4 (procedural with strict mode) | MQL5 (full object-oriented programming, classes, templates) |
| Debugging & Profiling | Basic visual debugging in tester | Advanced breakpoints, call stack, and tick/time code profiler |
| Version Control | Manual file backup or external Git | Integrated MQL5 Storage cloud repository and Git support |
| Code Completion (IntelliSense) | Standard function auto-complete | Enhanced IntelliSense with parameters, struct members, and doc snippets |
| Project & Multi-File Support | Individual file compilation with #include | Dedicated .mqproj projects, shared include directories, and resource packing |
IDE architecture
Key Components of the MetaEditor Workspace
MetaEditor is structured into dedicated modular panels for project navigation, code authoring, compilation diagnostics, and performance analysis.
Navigator Window
Tree structure organising MQL source directories: Experts (EAs), Indicators, Scripts, Include headers, Libraries, and Projects.
Code Editor & IntelliSense
Syntax highlighted editor featuring bracket matching, code folding, auto-formatting, line numbering, and contextual function parameter hints.
Built-in MQL Reference (F1)
Offline documentation accessible by placing the cursor on any MQL keyword or function and pressing F1, providing syntax, signatures, and code examples.
Toolbox & Errors Panel
Displays compilation messages, error codes, line numbers, search results, and MQL5 Storage repository sync status.
Debugger & Call Stack
Set breakpoints in source code, step through execution line by line, inspect local variables, and monitor call stack frames in real time.
Performance Profiler (ME5)
Measures execution speed and function call frequencies across historical price data, pinpointing algorithmic bottlenecks.
Step-by-step guide
MetaEditor 5 Tutorial: From New Project to Execution
Follow this five-step walkthrough to create, code, compile, and execute your first automated program in MetaTrader 5.
1
Open MetaEditor and Launch MQL Wizard
Press F4 in MetaTrader to launch MetaEditor. Click "New" (or Ctrl+N) to open the MQL Wizard, which generates boilerplate structure.
2
Select Program Type
Choose whether to create an Expert Advisor (automated trading), Custom Indicator (chart visualization), Script (single-run utility), or Include file.
3
Define Inputs and Event Handlers
Specify input parameters (such as lot size or moving average period) and select event handlers (OnInit, OnTick, OnTimer, OnDeinit).
4
Write Trading Logic and Compile (F7)
Add your trading calculations inside OnTick(). Press F7 to compile. Inspect the Errors tab to verify 0 errors and 0 warnings.
5
Execute on MetaTrader Chart
Switch back to MetaTrader (F4). Locate your program under Navigator -> Expert Advisors and drag it onto an active price chart.
Common MetaEditor Compilation Errors & Fixes
When compiling in MetaEditor with F7, compiler errors appear in the Toolbox panel. Here is how to resolve the most common diagnostic errors.
undeclared identifier '...' Root Cause
Variable or function name is misspelled or used before being declared in scope.
Solution
Declare the variable type (such as double, int, or string) before usage, or check header includes.
implicit conversion from '...' to '...'Root Cause
Assigning incompatible data types without explicit type casting (such as string to number).
Solution
Use explicit conversion functions like StringToDouble(), DoubleToString(), or IntegerToString().
array out of rangeRoot Cause
Accessing an array index that exceeds its allocated element size or history buffer limit.
Solution
Verify ArraySize() or use ArrayResize(), and check buffer index boundaries inside calculation loops.
unresolved function call '...'Root Cause
Calling a function whose declaration or library header is missing from the file.
Solution
Verify #include directives and ensure required .mqh header files reside in the MQL4/Include or MQL5/Include directory.
Pineify AI Coding Agents
Draft Clean MQL Code Before Opening MetaEditor
MetaEditor is your compiler and local runtime linker. Pineify MQL4 and MQL5 AI Coding Agents assist by drafting complete, syntax-checked single-file source code from plain English specifications.
Recommended 4-Step Development Cycle
- 1. Describe trading rules and indicators in plain English in Pineify.
- 2. Review the generated single-file .mq4 or .mq5 artifact and syntax diagnostics.
- 3. Copy the clean code into MetaEditor and press F7 to compile.
- 4. Backtest the compiled EA in the MetaTrader Strategy Tester.
Static checks do not guarantee market profitability. Always test thoroughly on demo accounts before live trading.
Related MetaTrader & Algorithmic Resources
MQL5 AI Coding Agent
Generate and revise editable MQL5 Expert Advisors, custom indicators, and scripts.
MQL4 AI Coding Agent
Create single-file MT4 Expert Advisors and indicators from natural language prompts.
Forex Trade Management Software
Automate lot sizing, trailing stops, break-even, and partial exits on MT4 and MT5.
MQL5 Guide Hub
Browse MetaTrader 5 code tutorials, indicator guides, and testing frameworks.
MQL5 Error Reference
Triage and resolve common MetaEditor compiler, runtime, and trade server errors.
MetaTrader 5 White Label Guide
Understand MT5 broker licensing, hosting architecture, APIs, and infrastructure scope.
Official Sources & Documentation
- MetaQuotes: MetaEditor 5 User GuideOfficial documentation on MetaEditor workspace, MQL Wizard, compilation, and debugging tools.
- MQL5 Reference DocumentationComprehensive reference covering MQL5 language syntax, standard library, and trade functions.
- MQL4 Reference DocumentationOfficial language reference for MQL4 programming and MetaTrader 4 functions.
This page provides technical software development and educational reference material, not financial or investment advice. Always test trading algorithms in a demo environment before connecting to live broker accounts.