How to Subtract the current price from the previous price (of 2 hours) any hints.

[tafadzwa]

 Can anyone show me how to subtract the current price from the previous price. Thanks!

[qjol]

pls explain, the current price or the price from 2 hrs ago ?

[William Roeder]

tafadzwa:  Can anyone show me how to subtract the current price from the previous price (of 2 hours)

1. If the chart period is small enough:

   #define HR0200  7200    // 2 * 3600
   double priceM2Hr = Close[HR0200/Period()];
   

   ---

2. If within one minute is close enough:

   #define HR0200  7200    // 2 * 3600
   datetime now  = TimeCurrent(),
            m2Hr = now - HR0200;                       // 2 hours ago
   int iM1 = iBarShift(NULL, PERIOD_M1, m2Hr);         // M1 bar 2 hours ago.
   double priceM2Hr = iClose(NULL, PERIOD_M1, iM1);

   ---

3. You insist on getting the price of a specific time you must keep every tick (price and time) in a dynamic array.
   
   Not compiled, not tested

   extern int TickHistoryMax.Seconds = 7200;
   int start(){
       SaveTick();
       datetime now = Timecurrent();
       double   twoHrAgo = GetTick(now - 7200);
       :
   }
   #define TICK_DT   0
   #define TICK_BID  1
       #define TICK_SIZE 2
   double ticks[][TICK_SIZE];
   void SaveTick(){
       int nBars = ArrayRange(ticks, 0);   ResizeBuffer(ticks, nBars+1);
       datetime now = TimeCurrent();
       ticks[0][TICK_DT] = now;        ticks[0][TICK_BID] = Bid;
   
       if (ticks[nBars][TICK_DT] - now > TickHistoryMax.Seconds*1.1){
           nBars = iGetTick(now + TickHistoryMax.Seconds);
           ArrayResize(ticks, nBars);
       }
   }
   double GetTick(datetime when){  return( ticks[iGetTick(when)][TICK_BID] );  }
   int iGetTick(datetime when){
       int iOld = ArrayRange(ticks, 0)-1;
       int iNew = 0;
       while(iOld < iNew){
           int iTm = (iOld+iNew)/2;
           if (tick[iTm] <= when)   iOld = iTm; else iNew = iTm - 1;
       }
       return(iTm);
   }
   bool    ResizeBuffer(double& buffer[], int size){
       if (ArrayRange(buffer,0) != size){      // ArrayRange allows 1D or 2D arrays
           ArraySetAsSeries(buffer, false);    // Shift values B[2]=B[1]; B[1]=B[0]
           if (ArrayResize(buffer, size) <= 0){ DisableTrading(
               "ArrayResize [2] failed: " + GetLastError() );  return(false);  }
           ArraySetAsSeries(buffer, true);
       }
       return(true);
   }
   

   Not compiled, not tested

[tafadzwa]

WHRoeder:

1. If the chart period is small enough:

   ---

2. If within one minute is close enough:

   ---

3. You insist on getting the price of a specific time you must keep every tick (price and time) in a dynamic array.
   
   Not compiled, not testedNot compiled, not tested

Thanks so much. Compiled an error shows up. Again thanks.