How to get the number of digits of the minimum volume?

[Martin Bittencourt]

Hi,

I'ld like to be able to know the number of decimal digits of the minimum volume/step of a symbol, something like _Digits but for volume. So suppose the min volume is "1": VolDigits = 0. Or min volume is "0.45": VolDigits = 2.

Searching in the forum I did manage to find another thread about this, but not only it's pretty old, but quite confusing. And I couldn't find anything native in MQL5 like _Digits either.

So, how can I do it? I though about transforming the number into a string and working that one, but I'm suspicious that won't work properly.

[William Roeder]

trying to get the number of decimal digits from a number (not a symbol) - Symbols - MQL4 programming forum (2015)

[Martin Bittencourt]

William Roeder #:

trying to get the number of decimal digits from a number (not a symbol) - Symbols - MQL4 programming forum (2015)

Thanks for pointing me that out! Unfortunately there are some many different codes there I really don't know which I should be using, especially given it is in MQL4's forum and not MQL5 ^.^ Do you have a suggestion?

[Ernst Van Der Merwe]

Martin Bittencourt #:

Thanks for pointing me that out! Unfortunately there are some many different codes there I really don't know which I should be using, especially given it is in MQL4's forum and not MQL5 ^.^ Do you have a suggestion?

int Digits(const double number)
  {
//---
   double num=number;
   int count=0;
   for(;count<8;count++) {
      if(!((int)num-num))
         return(count);
      num*=10; }
//---
   return(count);
  }         

[Dominik Egert]

Here is another way to ge the digits of a number.

//+------------------------------------------------------------------+
//| MathDigits                                                       |
//+------------------------------------------------------------------+

// Function
template <typename T>
const int MathDigits(const T value)
{ return((int)MathRound(MathAbs(MathLog10((double)value)))); }

// Inline macro
#define inline_MathDigits(value) ((int)MathRound(MathAbs(MathLog10((double)value))))

[amrali]

Please take a look at the Math Utis library

https://www.mql5.com/en/code/20822

// Get number of fractional digits after the decimal point.
int    GetDigits(double num);

// Get number of integer digits to the left of decimal point.
int    GetIntegerDigits(double num);

//+------------------------------------------------------------------+
//| Get number of fractional digits after the decimal point.         |
//+------------------------------------------------------------------+
int GetDigits(double num)
  {
   int d = 0; double p = 1;
   while(MathRound(num * p) / p != num)
     {
      p = MathPow(10, ++d);
     }
   return d;
  }

//+------------------------------------------------------------------+
//|                                                                  |
//+------------------------------------------------------------------+
void OnStart()
  {
   Print("======== Testing GetDigits() ========");  
   Print( GetDigits(1.13113) );  // The correct output should be 5
  }

[Martin Bittencourt]

Well, thanks people for all your replies! :) I ended up using the following:

int countDigits(const double val, const int maxPrecision = 8)
{ //https://www.mql5.com/en/forum/385354
   int digits = 0;
   
   while (NormalizeDouble(val,digits) != NormalizeDouble(val,maxPrecision))
      ++digits;

   return digits;
}

[William Roeder]

Dominik Christian Egert #: Here is another way to ge the digits of a number.

Fails if the number is not an exact power of 10, e.g. 0.5

[Danil Poletavkin]

amrali #:
int GetDigits(double num)   {    int d = 0; double p = 1;    while(MathRound(num * p) / p != num)      {       p = MathPow(10, ++d);      }    return d;   }

Thank you!