关于MQL4中EA订单数组存储及多EA同品种订单追踪的技术咨询

Great questions—let's dive into each one with practical MQL4 context:

1. Storing Orders in an EA Array vs. Using Built-in Order... Commands #

There's no one-size-fits-all answer, but here's a breakdown of tradeoffs to help you decide:

Pros of using a local array #

• Reduced server/network dependency: Every call to OrderSelect(), OrderGetTicket(), or similar commands hits the MT4 server. If your network is spotty, this can cause delays or failed queries. A local array cuts down on these external calls entirely for routine checks.
• Faster access: Querying an array is instant, which is a big plus if your EA needs to check order statuses every tick or execute high-frequency logic.

Cons of using a local array #

• Heavy maintenance burden: You have to manually sync the array with the actual server order book. That means handling every possible order event—new orders, modifications, closures, broker cancellations, even manual user actions. Miss one event, and your array data becomes outdated and unreliable.
• Edge case complexity: For example, if a user closes an order manually or the broker adjusts a stop loss, your EA won't know unless you build in periodic reconciliation checks (like syncing with the server every 5 seconds). This adds extra code complexity.

My recommendation #

• If your EA does frequent order operations (e.g., monitoring positions every tick for exit conditions), go with a local array—but pair it with periodic server syncs to keep data accurate.
• If your EA only interacts with orders occasionally (e.g., opening a single position once per hour), stick to the built-in Order... commands. They're simpler, less error-prone, and you don't have to handle the sync headache.

2. Tracking Orders from Two Different EAs on the Same Symbol #

The standard, most reliable method is using magic numbers—here's how to implement it:

Step 1: Assign unique magic numbers to each EA #

When opening orders in each EA, set a distinct magic parameter in the OrderSend() function. This number acts as a unique identifier for all orders from that EA:

// For EA 1, use magic number 12345
int ea1Ticket = OrderSend(Symbol(), OP_BUY, 0.1, Ask, 3, Bid - 50*Point, Ask + 50*Point, "EA1 Long", 12345, 0, Green);

// For EA 2, use magic number 67890
int ea2Ticket = OrderSend(Symbol(), OP_SELL, 0.1, Bid, 3, Ask + 50*Point, Bid - 50*Point, "EA2 Short", 67890, 0, Red);

Step 2: Filter orders by magic number #

When you need to track orders from a specific EA, filter using OrderMagicNumber() when iterating through orders:

// Example: Find all orders from EA1 on the current symbol
for(int i = OrdersTotal() - 1; i >= 0; i--) {
    if(OrderSelect(i, SELECT_BY_POS, MODE_TRADES)) {
        if(OrderMagicNumber() == 12345 && OrderSymbol() == Symbol()) {
            // This is an order from EA1
            Print("EA1 Order Ticket: ", OrderTicket(), " | Type: ", OrderType());
        }
    }
}

Bonus tips #

• Add a unique comment (like the EA name) to each order in the OrderSend() comment parameter. This makes it easy to verify orders manually in the MT4 terminal.
• Avoid using magic number 0 unless you want to track unlabeled orders—many manual orders default to 0, so it can cause confusion.

内容的提问来源于stack exchange，提问作者Jean