How developers use certain functions, variables and conditions to create an Expert advisor

Hi friends, today we look at some great examples to get you going as a software developer

First we will look at a function we call (Init) or Initialize

This function is executed once when the EA is loaded or when the trading conditions change. It is used to initialize variables, set parameters, and perform any necessary setup.

Here's an example:

void OnInit()
{
    // Initialize variables and parameters
    double lotSize = 0.1;
    int stopLoss = 50;
    int takeProfit = 100;

    // Perform setup operations
    // ...
}

Then we have something we call, conditions. In this case, Entry conditions.

These conditions determine when to enter a trade. They typically involve technical indicators, price levels, or specific patterns.

Here's an example using a simple moving average crossover strategy:

bool ShouldEnterTrade()
{
    double maFast = iMA(Symbol(), PERIOD_M15, 5, 0, MODE_SMA, PRICE_CLOSE, 0);
    double maSlow = iMA(Symbol(), PERIOD_M15, 10, 0, MODE_SMA, PRICE_CLOSE, 0);

    if (maFast > maSlow)
        return true;

    return false;
}

Next we have EXIT conditions.

These conditions determine when to exit a trade, either by taking profit or cutting losses. They can be based on target profit levels, stop-loss orders, or trailing stops.

Here's an example using a fixed stop loss and take profit:

bool ShouldExitTrade()
{
    double entryPrice = OrderOpenPrice();
    double currentPrice = SymbolInfoDouble(Symbol(), SYMBOL_BID);

    if (currentPrice - entryPrice >= takeProfit || entryPrice - currentPrice >= stopLoss)
        return true;

    return false;
}

Next we have a typical term we call, Money management.

Money management functions are used to calculate position sizes and manage risk. They consider factors like account balance, risk tolerance, and desired risk-to-reward ratios. Here's an example using a fixed lot size:

double CalculateLotSize()
{
    return 0.1; // Fixed lot size
}

Then Trade executions:

Trade execution functions are used to open and close positions based on the defined entry and exit conditions.

Here's an example of opening a buy trade:

void EnterBuyTrade()
{
    double lotSize = CalculateLotSize();
    int slippage = 3;

    OrderSend(Symbol(), OP_BUY, lotSize, Ask, slippage, 0, 0, "Buy Order", MagicNumber, 0, Green);
}

Now lets see what all of this means:

1. void : 

2. In programming, void is a keyword used to indicate that a function does not return any value. When a function is declared as void , it means that it performs certain operations or tasks but does not produce an output or result. For example, an initialization function ( void OnInit() ) in an expert advisor may be used to set up variables, parameters, and perform necessary setup operations without returning any specific value.

3. bool : 

4. bool is short for "boolean" and represents a data type that can have one of two values: true or false . It is commonly used to store and evaluate logical conditions. In the context of an expert advisor, bool is often used to define conditions for making decisions. For instance, a function like bool ShouldEnterTrade()may evaluate certain indicators or market conditions and return true if the conditions for entering a trade are met, and false otherwise.

5. OrderSend : 

6. OrderSendis a function used in MetaTrader platforms to send trading orders. It is responsible for executing trade actions, such as opening or closing positions. The function requires several parameters, including the symbol, order type (buy or sell), lot size, entry price, slippage, stop loss, take profit, and other optional parameters. The OrderSendfunction allows the expert advisor to interact with the trading platform and execute trades based on the predefined conditions and strategies.

7. double : 

8. double is a data type used to store decimal numbers with a higher precision compared to integers. It is commonly used to represent prices, indicators, profit/loss values, and other numeric data in trading. In the context of an expert advisor, double is often used to store variables and perform calculations involving decimal values. For example, variables like stopLoss or takeProfit can be declared as double to store the desired stop loss and take profit levels for a trade.

In summary, voidindicates a function that doesn't return a value, bool is a data type used for logical conditions, OrderSendis a function used to send trading orders, and doubleis a data type used for decimal numbers and calculations. These concepts and functions play crucial roles in programming expert advisors to define logic, make decisions, and execute trades in automated trading systems.

Hope it helps.

Enjoy....