The function is called in EAs when the NewTick event occurs to handle a new quote.

void  OnTick(void);

Return Value

No return value


The NewTick event is generated only for EAs upon receiving a new tick for a symbol of the chart the EA is attached to. There is no point in defining the OnTick() function in a custom indicator or a script since a NewTick event is not generated for them.

The Tick event is generated only for EAs, but this does not mean that EAs have to feature the OnTick() function, since Timer, BookEvent and ChartEvent events are also generated for EAs in addition to NewTick.

All events are handled one after another in the order of their receipt. If the queue already contains the NewTick event or this event is in the processing stage, then the new NewTick event is not added to mql5 application queue.

The NewTick event is generated regardless of whether auto trading is enabled (AutoTrading button). Disabled auto trading means only a ban on sending trade requests from an EA. The EA operation is not stopped.

Disabling auto trading by pressing the AutoTrading button does not interrupt the current execution of the OnTick() function.

Example of the EA featuring its entire trading logic in the OnTick() function

//|                                                   TradeByATR.mq5 |
//|                        Copyright 2018, MetaQuotes Software Corp. |
//|                                             https://www.mql5.com |
#property copyright "Copyright 2018, MetaQuotes Software Corp."
#property link      "https://www.mql5.com"
#property version   "1.00"
#property description "Sample EA trading in the \"explosive\" candle direction"
#property description "\"Explosive\" candle has the body size exceeding k*ATR"
#property description "The \"revers\" parameter reverses the signal direction"
input double lots=0.1;        // volume in lots
input double kATR=3;          // signal candle length in ATR
input int    ATRperiod=20;    // ATR indicator period
input int    holdbars=8;      // number of bars to hold position on
input int    slippage=10;     // allowable slippage
input bool   revers=false;    // reverse the signal? 
input ulong  EXPERT_MAGIC=0;  // EA's MagicNumber
//--- for storing the ATR indicator handle
int atr_handle;
//--- here we will store the last ATR values and the candle body
double last_atr,last_body;
datetime lastbar_timeopen;
double trade_lot;
//| Expert initialization function                                   |
int OnInit()
//--- initialize global variables
//--- set the correct volume
   double min_lot=SymbolInfoDouble(_Symbol,SYMBOL_VOLUME_MIN);
   trade_lot=lots>min_lot? lots:min_lot;   
//--- create ATR indicator handle
      PrintFormat("%s: failed to create iATR, error code %d",__FUNCTION__,GetLastError());
//--- successful EA initialization
//| Expert deinitialization function                                 |
void OnDeinit(const int reason)
//--- inform of the EA operation end code
   Print(__FILE__,": Deinitialization reason code = ",reason);
//| Expert tick function                                             |
void OnTick()
//--- trading signal
   static int signal=0; // +1 means a buy signal, -1 means a sell signal
//--- check and close old positions opened more than 'holdbars' bars ago
//--- check for a new bar
      //--- check for a signal presence      
//--- if a netting position is opened, skip the signal - wait till it closes
      return// exit the NewTick event handler and do not enter the market before a new bar appears
//--- for a hedging account, each position is held and closed separately
      //--- buy signal
         PrintFormat("%s: Buy signal! Revers=%s",__FUNCTION__,string(revers));
      //--- sell signal
         PrintFormat("%s: Sell signal! Revers=%s",__FUNCTION__,string(revers));
//--- OnTick function end
//| Check for a new trading signal                                   |
int CheckSignal()
//--- 0 means no signal
   int res=0;
//--- get ATR value on a penultimate complete bar (the bar index is 2)
   double atr_value[1];
      //--- get data on the last closed bar to the MqlRates type array
      MqlRates bar[1];
         //--- calculate the bar body size on the last complete bar
         //--- if the body of the last bar (with index 1) exceeds the previous ATR value (on the bar with index 2), a trading signal is received
            res=last_body>0?1:-1; // positive value for the upward candle
         PrintFormat("%s: Failed to receive the last bar! Error",__FUNCTION__,GetLastError());
      PrintFormat("%s: Failed to receive ATR indicator value! Error",__FUNCTION__,GetLastError());
//--- if reverse trading mode is enabled
   res=revers?-res:res;  // reverse the signal if necessary (return -1 instead of 1 and vice versa)
//--- return a trading signal value
   return (res);
//|  Return 'true' when a new bar appears                            |
bool isNewBar(const bool print_log=true)
   static datetime bartime=0; // store open time of the current bar
//--- get open time of the zero bar
   datetime currbar_time=iTime(_Symbol,_Period,0);
//--- if open time changes, a new bar has arrived
      //--- display data on open time of a new bar in the log      
      if(print_log && !(MQLInfoInteger(MQL_OPTIMIZATION)||MQLInfoInteger(MQL_TESTER)))
         //--- display a message with a new bar open time
         PrintFormat("%s: new bar on %s %s opened at %s",__FUNCTION__,_Symbol,
         //--- get data on the last tick
         MqlTick last_tick;
            Print("SymbolInfoTick() failed, error = ",GetLastError());
         //--- display the last tick time up to milliseconds
         PrintFormat("Last tick was at %s.%03d",
      //--- we have a new bar
      return (true);
//--- no new bar
   return (false);
//| Buy at a market price with a specified volume                    |
bool Buy(double volume,ulong deviation=10,ulong  magicnumber=0)
//--- buy at a market price
   return (MarketOrder(ORDER_TYPE_BUY,volume,deviation,magicnumber));
//| Sell at a market price with a specified volume                   |
bool Sell(double volume,ulong deviation=10,ulong  magicnumber=0)
//--- sell at a market price
   return (MarketOrder(ORDER_TYPE_SELL,volume,deviation,magicnumber));
//| Close positions by hold time in bars                             |
void ClosePositionsByBars(int holdtimebars,ulong deviation=10,ulong  magicnumber=0)
   int total=PositionsTotal(); // number of open positions   
//--- iterate over open positions
   for(int i=total-1; i>=0; i--)
      //--- position parameters
      ulong  position_ticket=PositionGetTicket(i);                                      // position ticket
      string position_symbol=PositionGetString(POSITION_SYMBOL);                        // symbol 
      ulong  magic=PositionGetInteger(POSITION_MAGIC);                                  // position MagicNumber
      datetime position_open=(datetime)PositionGetInteger(POSITION_TIME);               // position open time
      int bars=iBarShift(_Symbol,PERIOD_CURRENT,position_open)+1;                       // how many bars ago a position was opened
      //--- if a position's lifetime is already large, while MagicNumber and a symbol match
      if(bars>holdtimebars && magic==magicnumber && position_symbol==_Symbol)
         int    digits=(int)SymbolInfoInteger(position_symbol,SYMBOL_DIGITS);           // number of decimal places
         double volume=PositionGetDouble(POSITION_VOLUME);                              // position volume
         ENUM_POSITION_TYPE type=(ENUM_POSITION_TYPE)PositionGetInteger(POSITION_TYPE); // position type
         string str_type=StringSubstr(EnumToString(type),14);
         StringToLower(str_type); // lower the text case for correct message formatting
         PrintFormat("Close position #%d %s %s %.2f",
         //--- set an order type and sending a trade request
//| Prepare and send a trade request                                 |
bool MarketOrder(ENUM_ORDER_TYPE type,double volume,ulong slip,ulong magicnumber,ulong pos_ticket=0)
//--- declaring and initializing structures
   MqlTradeRequest request={0};
   MqlTradeResult  result={0};
   double price=SymbolInfoDouble(Symbol(),SYMBOL_BID);
//--- request parameters
   request.action   =TRADE_ACTION_DEAL;                     // trading operation type
   request.position =pos_ticket;                            // position ticket if closing
   request.symbol   =Symbol();                              // symbol
   request.volume   =volume;                                // volume 
   request.type     =type;                                  // order type
   request.price    =price;                                 // trade price
   request.deviation=slip;                                  // allowable deviation from the price
   request.magic    =magicnumber;                           // order MagicNumber
//--- send a request
      //--- display data on failure
      PrintFormat("OrderSend %s %s %.2f at %.5f error %d",
      return (false);
//--- inform of a successful operation
   PrintFormat("retcode=%u  deal=%I64u  order=%I64u",result.retcode,result.deal,result.order);
   return (true);

See also

Event handling functions, Program running, Client terminal events, OnTimer, OnBookEvent, OnChartEvent