How to manage JPY pairs with parameters?

You could first declare the variables and then assign their values.

Also note that you can find these JPY pairs and others like GOLD and etc.. by simply analyzing:

So there is no need to hard code all the symbol names into the code and a simple multiplier related to digits can be a lot easier and will also work for symbols that you didn't include in your code.

1. Frenchytrader: Now It says I have undeclared variables: so I did this way: I added "double"
   

         /// --- Prepare data --- ///
                   if (Symbol()=="AUDJPY" || Symbol()=="CADJPY" || Symbol()=="CHFJPY" || Symbol()=="EURJPY" || Symbol()=="GBPJPY" || Symbol()=="USDJPY" || Symbol()=="NZDJPY" )
                  {double Modify_StopLoss_v1 = Modify_StopLoss*100;  double Pips_Marge_v1 = Pips_Marge*100;  double Check_Spread_v1=Check_Spread*100; double Modify_Entry_v1 = Modify_Entry*100; double Daily_Candle_Pips_v1 = Daily_Candle_Pips*100;}
                 
            else  {double Modify_StopLoss_v1 = Modify_StopLoss;  double Pips_Marge_v1 = Pips_Marge;   double Check_Spread_v1=Check_Spread;  double Modify_Entry_v1 = Modify_Entry;  double Daily_Candle_Pips_v1 = Daily_Candle_Pips;}  
   

   But with JPY pairs... it doesn't convert my parameter with 2 zero less ?
   
   Using strict mode, variables declared inside the braces "{}" are not visible after the closing brace. Thus your error and #1's suggestion.
   
2.  You are not adjusting SL, TP, and slippage for 4/5 digit brokers and for JPY pairs.
         /// --- Prepare data --- ///
   double   pip          = StringFind(_Symbol,"JPY") < 0 ? 0.01 : 0.0001;
   int      pipDigits    = (int)MathLog10(pip/_Point);
   int      pipsToPoints = int(pip / _Point);
   int      slippage     = 3 * pipsToPoints;
   
   double Modify_StopLoss_v1   = Modify_StopLoss   * pipsToPoints; // \   Or just drop all these
   double Pips_Marge_v1        = Pips_Marge        * pipsToPoints; //  \  variables, and just use
   double Check_Spread_v1      = Check_Spread      * pipsToPoints; //   > Check_Spread * pip, etc.,
   double Modify_Entry_v1      = Modify_Entry      * pipsToPoints; //  /  instead of
   double Daily_Candle_Pips_v1 = Daily_Candle_Pips * pipsToPoints; // /   Check_Spread_v1 * _Point
   

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3. Marco vd Heijden: Also note that you can find these JPY pairs and others like GOLD and etc.. by simply analyzing:
   
   The term pip is only defined for currencies, not metals. What is a TICK? - MQL4 forum  Analyzing digits or just looking for JPY will not work for exotics like USDMXN/USDZAR where the spread is beyond 300 pips. For that I've been trying
   double dvpl = DeltaValuePerLot();
   double pip  = 0.0001;
   while(dvpl * pip < 5) pip *= 10;
   Which gives the same results for most currencies, adjusts for the exotics, and should handle metals, i.e. a pip is worth about ¤10 (account currency.)