MQL5 examples: working code for MetaTrader 5

How to run an example

Each page says whether its program is an Expert Advisor, which stays on its chart and reacts to every tick until you remove it, or a script, which runs once when you drop it on a chart.

1. In MetaTrader 5, open File > Open Data Folder, then MQL5/Experts for an Expert Advisor or MQL5/Scripts for a script, and save the downloaded .mq5 file there.
2. Open it in MetaEditor and press F7 (Compile). The Errors tab should end with “0 errors, 0 warnings”.
3. Back in the terminal, drag the program from the Navigator onto a chart. Programs that trade need the Algo Trading button on and “Allow Algo Trading” ticked in their settings.
4. Start on a demo account. For an Expert Advisor, run it in the Strategy Tester first.

The full walk-through, with the usual problems and their fixes, is in how to install an Expert Advisor on MT5.

What every example does the same way

The programs are short, but they follow the rules that keep code working on real brokers, so you can lift a function into your own EA:

• Orders go through the standard library's CTrade, and every result is checked with ResultRetcode(): a true return only means the request was sent.
• Prices are rounded to the symbol's tick size and volumes to its volume step, never to a fixed number of decimals.
• Stops are measured from the price a position closes at: the Bid for a buy, the Ask for a sell.
• Only positions with the program's symbol and magic number are touched, so manual trades and other EAs are left alone.
• Indicator handles are created once in OnInit(), and signals are read on closed bars.
• Anything that must survive a restart, such as the trades taken today or a partial close already done, is read from the server's deal history rather than kept in a variable.