How to count positions of symbol(s)

Hi everyone, I'm designing a Multi-Symbol EA

and I tried to count every position of each symbol

method of symbol splitting  

input string TradeSymbols = "EURUSD,GBPJPY,AUDNZD,CADCHF";
      string SymbolArray [];
      int         SymbolsNo; // Number of Symbols

//+------------------------------------------------------------------+
//| Expert initialization function                                   |
//+------------------------------------------------------------------+
int OnInit()
            {
             SymbolsNo= StringSplit(TradeSymbols, ',' , SymbolArray);
             
             if (_Digits==4 || _Digits<=2) MyPoint=_Point;
             if (_Digits==3 || _Digits==5) MyPoint=_Point*10;   
              return(INIT_SUCCEEDED);
            }

To count buy positions of each symbol

int Buys()
          {
            int B=0,i,j;
            for ( i=0; i<PositionsTotal();  i++)
                                                { 
                                                 if 
                                                   (
                                                        
                                                        SymbolArray[j]  == PositionGetSymbol(i) 
                                                     && MagicNumber==PositionGetInteger(POSITION_MAGIC)
                                                     && PositionGetInteger(POSITION_TYPE) == POSITION_TYPE_BUY
                                                   )
                                                                              
                                                                              
                                                   { B++;}
                                                }
          return(B);
        }

I wanted to use the same variable (j) on my conditions in OnTick

void OnTick()
  { 
    for (int j=0; j<SymbolsNo; j++)
      { if Buys()<1 ) 
         { 
            ............conditions & functions of (j)'s
         }
  }

 Where's my mistake?