//+------------------------------------------------------------------+
//|                                                   debug_demo.mq5 |
//|                                        Copyright © 2018, Amr Ali |
//|                             https://www.mql5.com/en/users/amrali |
//+------------------------------------------------------------------+
#property copyright "Copyright © 2018, Amr Ali"
#property link      "https://www.mql5.com/en/users/amrali"
#property version   "4.0"

#include <math_utils.mqh>
//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
#define PRINT(A) Print(#A + " = ", (A))

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
void OnStart()
  {
   double a = 0.1;
   double b = 0.2;

//--- Example of where exact comparison of doubles can fail:
   if(a + b == 0.3)
     {
      Print("This should be the expected result.");
     }
   else
     {
      Print("Too bad comparison!");
     }

//--- Debugging floating-point numbers can help.
   Print( a + b );                        // 0.30000000000000004
   Print( 0.3 );                          // 0.3

   PRINT( DoubleToStringExact(a + b) );   // 0.300000000000000044408920985006261616945266723632812500
   PRINT( DoubleToStringExact(0.3) );     // 0.299999999999999988897769753748434595763683319091796875

   PRINT( DoubleToHexadecimal(a + b) );   // 0x3FD3333333333334
   PRINT( DoubleToHexadecimal(0.3) );     // 0x3FD3333333333333

   PRINT( UlpDiff(a + b, 0.3) );          // 1
   PRINT( NextAfter(0.3) == a + b );      // true
  }
//+------------------------------------------------------------------+

/* output:
   Too bad comparison!
   0.30000000000000004
   0.3
   DoubleToStringExact(a+b) = 0.300000000000000044408920985006261616945266723632812500
   DoubleToStringExact(0.3) = 0.299999999999999988897769753748434595763683319091796875
   DoubleToHexadecimal(a+b) = 0x3FD3333333333334
   DoubleToHexadecimal(0.3) = 0x3FD3333333333333
   UlpDiff(a+b,0.3) = 1
   NextAfter(0.3)==a+b = true
*/