A simple expert advisor scanning multiple codes

I am very novice in programming a robot and I would like to develop the following EA. Overall the robot is looping continuously over a large number of symbols performing a few calculations on those symbols prices and deciding if it wants to buy or sell. I want no two open positions for the same symbol and also no position exchange (no positions should be closed to open new ones). For each open position of a symbol, the robot will need to find the buying price for that position and the day the position was opened as this is important information for determining the selling point.

I am not sure if one script can loop over several symbols (some users suggest that each tick function can only be employed on a single symbol). I am open to your suggestions (possibly copying pasting the code multiple times to scan various symbols or similar solution. I will need a couple of market days to test the code myself. See below for full annotation:

void OnTick()

  {

\\ Define a list of codes (approximately 500 codes in reality) to be checked. I have unsuccessfully tried defining an array and looping through those symbols. Possibly this is not the right solution (maybe you need to run OnTicks for each code separately. )

string symbol_array[]={"XOM","AAL","ABNB"};

int number_of_symbols=ArraySize(symbol_array);

Print("Total number of symbols is =",number_of_symbols);

for(int symbol_position=1;symbol_position<=number_of_symbols;symbol_position++)

{string stockname=symbol_array[symbol_position];

Print("Current symbol is =",stockname); 

double   Current_close = iClose(stockname,PERIOD_M1,0);

double   Close_minus1 = iClose(stockname,PERIOD_M1,1);

double   Close_minus2 = iClose(stockname,PERIOD_M1,2);

double   Close_minus3 = iClose(stockname,PERIOD_M1,3);

double   High_minus_1day = iHigh(stockname,PERIOD_D1,1);

double   High_minus_2day = iHigh(stockname,PERIOD_D1,2);

double   High_minus_3day = iHigh(stockname,PERIOD_D1,3);

double   High_minus_4day = iHigh(stockname,PERIOD_D1,4);

double   High_minus_5day = iHigh(stockname,PERIOD_D1,5);

double   High_minus_6day = iHigh(stockname,PERIOD_D1,6);

double   High_minus_7day = iHigh(stockname,PERIOD_D1,7);

double   High_minus_8day = iHigh(stockname,PERIOD_D1,8);

double   Trending_pattern = (High_minus_4day+High_minus_3day+High_minus_2day+High_minus_1day) - (High_minus_8day+High_minus_7day+High_minus_6day+High_minus_5day);

double   Percentage_move3 = (Current_close-Close_minus3)/Close_minus3;

double   Percentage_move2 = (Current_close-Close_minus2)/Close_minus2;

double   Percentage_move1 = (Current_close-Close_minus1)/Close_minus1;

double   Local_derivative = Close_minus2/2 - 2*Close_minus1 +3*Current_close/2;

\\ Generate a buy signal IF Trending_pattern>0 && Local_derivative>0.05 && NO orders are pending for this code and NO positions are open for this code.

I do not want to exchange (close positions to open new ones) any currently open position. I do not know how to implement the 'NO orders should be pending and the 'NO open positions should exist for this code' parts. Please help me with this.

//buy signal

if ( Trending_pattern>0 && Local_derivative>0.05 && OrdersTotal()==0 )

{

   MqlTradeRequest request={0};

   MqlTradeResult  result={0};

//--- parameters of request

   request.action   =TRADE_ACTION_DEAL;                     // type of trade operation

   request.symbol   =stockname;                              // symbol

   request.volume   =1;                                   // volume of 0.1 lot

   request.type     =ORDER_TYPE_BUY;                        // order type

   request.deviation=5;    

OrderSend(request,result);

}

\\ Generate a SELL signal IF 'the current selling price Current_close of an open position for the current code is 1.1 times the price I have bought it in the past' OR 'the position for this code was opened more than 3 days ago'.

I do not know how to implement either of these 2 conditions. Please help me with that.

//sell signal

if (Current_close >1.1*Price_paid_for_position)

{

   MqlTradeRequest request={0};

   MqlTradeResult  result={0};

//--- parameters of request

   request.action   =TRADE_ACTION_DEAL;                     // type of trade operation

   request.symbol   =stockname;                              // symbol

   request.volume   =0.1;                                   // volume of 0.1 lot

   request.type     =ORDER_TYPE_SELL;                        // order type

   request.deviation=5;   

OrderSend(request,result);

}