EA是什么？及他的工作原理 二
四、源码的交易流程分析下面的源码是一个基于移动平均线的智能交易系统的代码 ，整个程序非常简洁但EA的功能又非常齐全，实现了完全由电脑自动下单和平仓，整个程序只用了一个START()
函数来实现 。程序代码分析
参看代码中的相关注释
//+------------------------------------------------------------------+
//| modifiedEA.mq4 |
//| Copyright ?2008, MetaQuotes Software Corp. |
//+------------------------------------------------------------------+
//---- input parameters
extern double TakeProfit = 20;
extern double StopLoss = 30;
extern double Lots = 2;
extern double TrailingStop = 50;
extern int ShortEma = 5;
extern int LongEma = 60;
//+------------------------------------------------------------------+
//| expert initialization function |
//+------------------------------------------------------------------+
int init()
{
//----
//----
return (0);
}
//+------------------------------------------------------------------+
//| expert deinitialization function |
//+------------------------------------------------------------------+
int deinit()
{
//----
//----
return (0);
}
//+------------------------------------------------------------------+
//| expert start function |
//+------------------------------------------------------------------+
int start()
{
int cnt, ticket, total;
double SEma, LEma;
//----
if (Bars < 100)
{
Print("bars less than 100");
return (0);
}
//----
if (TakeProfit < 10)
{
Print("TakeProfit less than 10");
return (0); // check TakeProfit
}
//----
SEma = iMA(NULL, 0, ShortEma, 0, MODE_EMA, PRICE_CLOSE, 0);
LEma = iMA(NULL, 0, LongEma, 0, MODE_EMA, PRICE_CLOSE, 0);
//----
static int isCrossed = 0;
isCrossed = Crossed(LEma, SEma);
//----
total = OrdersTotal();
if (total < 1)
{
if (isCrossed == 1) // 满足空仓条件，开空仓
{
ticket = OrderSend(Symbol(), OP_SELL, Lots, Bid, 3, Bid + StopLoss * Point,
Bid - TakeProfit * Point, "EMA_CROSS", 12345, 0, Green);
if (ticket > 0)
{
if (OrderSelect(ticket, SELECT_BY_TICKET, MODE_TRADES))
Print("SELL order opened : ", OrderOpenPrice());
} else
Print("Error opening SELL order : ", GetLastError());
return (0);
}
if (isCrossed == 2) // 满足多仓条件，开多仓
{
ticket = OrderSend(Symbol(), OP_BUY, Lots, Ask, 3, Ask - StopLoss * Point,
Ask + TakeProfit * Point, "EMA_CROSS", 12345, 0, Red);
if (ticket > 0)
{
if (OrderSelect(ticket, SELECT_BY_TICKET, MODE_TRADES))
Print("BUY order opened : ", OrderOpenPrice());
} else
Print("Error opening BUY order : ", GetLastError());
return (0);
}
return (0);
}
//---- 订单修改，实现动态止盈止损跟踪
for (cnt = 0; cnt < total; cnt++)
{
OrderSelect(cnt, SELECT_BY_POS, MODE_TRADES);
if (OrderType() <= OP_SELL && OrderSymbol() == Symbol())
{
if (OrderType() == OP_SELL) // long position is opened
{
// check for trailing stop
if (TrailingStop > 0)
{
if (Bid - OrderOpenPrice() > Point * TrailingStop)
{
if (OrderStopLoss() < Bid - Point * TrailingStop)
{
OrderModify(OrderTicket(), OrderOpenPrice(),
Bid - Point * TrailingStop,
OrderTakeProfit(), 0, Green);
return (0);
}
}
}
} else // go to short position
{
// check for trailing stop
if (TrailingStop > 0)
{
if ((OrderOpenPrice() - Ask) > (Point * TrailingStop))
{
if ((OrderStopLoss() > (Ask + Point * TrailingStop)))
{
OrderModify(OrderTicket(), OrderOpenPrice(),
Ask + Point * TrailingStop,
OrderTakeProfit(), 0, Red);
return (0);
}
}
}
}
}
}
//----
return (0);
}
//+------------------------------------------------------------------+
// 移动平均线多空条件判断，
int Crossed(double line1, double line2)
{
static int last_direction = 0;
static int current_direction = 0;
//Don't work in the first load, wait for the first cross!
static bool first_time = true;
if (first_time == true)
{
first_time = false;
return (0);
}
//----
if (line1 > line2)
current_direction = 2; //up 多头市场 上穿做多
if (line1 < line2)
current_direction = 1; //down 空头市场 下穿做空
//----
if (current_direction != last_direction) //changed 多空改变 {
last_direction = current_direction;
return (last_direction);
else return (0); //not changed
}
五、本文结论
从以上的分析,可以知道，所谓EA，就是由电脑模拟交易员的下单操作进行机器交易的过程, 具体步骤如下：1。当用户打开外汇客户端程序后，由客户端程序调入用户在系统内已预置好的EA交易系统程序。2。当EA程序启动后便开始对图表中货币对的K线趋势图，进行监视，寻找开仓的条件；3。如果条件满足，进行下单开仓(做多或者做空)；
4。重复第二步，继续盯盘，假定第二步是开仓，就是寻找平仓的条件。
5。如果平仓的条件满足，进行平仓操作，计算盈亏核算。完成一次交易的循环。
6。若继续交易，EA重复2->3->4->5步
7。用户若不想让EA进行交易，可通过相关菜单操作设置禁用EA，或者退出外汇客户端。
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