Floatingpoint has an infinite number of decimals, it's you, not understanding floatingpoint and that some numbers can't be represented exactly. (like 1/10.)
Doubleprecision floatingpoint format  Wikipedia
See also The == operand.  MQL4 programming forum (2013)
If you want to see the correct number of digits, convert it to a string with the correct/wanted accuracy.
question about decima of marketinfo()  MQL4 programming forum (2016)
Hi William , Tanks for reply.
I don't know if i made something wrong. could be, and that's why i asked your help.
as i said i just made the istruction you suggested , specfically :
string VS = DoubleToString( VS1 , 2 ); and i get "0.01" then
VolumeStep = StringToDouble( VS); and get the same value = 0.100000000000000006
but the strange thing is why when I made the istruction
So at the end if this instruction seem to be ignored how can I check a value returned by VS1 = NormalizeDouble(VolumeStep , 2); with a constant like
if ( VS1 == 0.01 ) .... this turn out is allways false ... isn't it ?
please , dont get me worng, i talked about strange behaviour not about someone fault. Im seeking help and appreciate the time you spend assisting us. but i have also about 20 years of programming on my shoulders and i know pretty well what is a double value.
if could be usefull i currently program in two other envireonment ( Net.core vith visual code C# language and codeblock CPP language. ) and neither of two present similar behaviour.
thank you if I can count on your help.
string VS = DoubleToString( VS1 , 2 ); and i get "0.01"”then
VolumeStep = StringToDouble( VS); and get the same value = 0.100000000000000006
 Of course, you do. VS1 is your VolumeStep
 I made no such suggestion. I said, “If you want to see the correct number of digits.”
Hi to all guys , I am new here,
recently while i was trying to code en EA and I noted that almost in any cases when i read values with a sample call like :
double VolumeStep = MarketInfo(symbol, SYMBOL_VOLUME_STEP); or
double MinVolume = MarketInfo(symbol, SYMBOL_VOLUME_MIN);
I get a strange value : 0.100000000000000006 instead of 0.01 as i expected
See this thread:
https://www.mql5.com/en/forum/440534
Actually, the debugger window displays the longest roundtrip string, while, Print() and input dialog boxes display the shortest roundtrip string. Both are accurate, but the longestround trip form is confusing and not intuitive.
 2023.01.26
 www.mql5.com
Hi amrali,
I read your post https://www.mql5.com/en/forum/440534 and i have to say "in a word" excellent. this is exactly the problem that I faced.
But also I think that, at least for me , it's not a cosmetic quetion becasue if you see this number in debugger it signifies that if you apply an arithmetic operation to this kind of number the digits count to the result.
so , as you said, in other languages that I use ( C# / Cpp ) and relative degugger this problem is not found.
what is still confusing me is that when i apply a function like NormalizeDouble(VolumeStep , 2); it seems that nothinig happens to the result. That's not good form me.
now : what is the next step ? I wold like to finish my EA for my daughter if any one has some suggestion is appreciate.
You used NormalizeDouble, It's use is usually wrong, as it is in your case.

Floating point has an infinite number of decimals, it's you were not understanding floating point and that some numbers can't be represented exactly. (like 1/10.)
Doubleprecision floatingpoint format  Wikipedia, the free encyclopediaSee also The == operand.  MQL4 programming forum (2013)

Print out your values to the precision you want with DoubleToString  Conversion Functions  MQL4 Reference.

SL/TP (stops) need to be normalized to tick size (not Point) — code fails on noncurrencies.
On 5Digit Broker Stops are only allowed to be placed on full pip values. How to find out in mql?  MQL4 programming forum (2011)And abide by the limits Requirements and Limitations in Making Trades  Appendixes  MQL4 Tutorial and that requires understanding floating point equality Can price != price ?  MQL4 programming forum (2012)

Open price for pending orders need to be adjusted. On Currencies, Point == TickSize, so you will get the same answer, but it won't work on noncurrencies. So do it right.
Trailing Bar Entry EA  MQL4 programming forum (2013)
Bid/Ask: (No Need) to use NormalizeDouble in OrderSend  MQL4 programming forum (2012) 
Lot size must also be adjusted to a multiple of LotStep and check against min and max. If that is not a power of 1/10 then NormalizeDouble is wrong. Do it right.
(MT4 2013)) (MT5 2022)) 
MathRound() and NormalizeDouble() are rounding in a different way. Make it explicit.
MT4:NormalizeDouble  MQL5 programming forum (2017)
How to Normalize  Expert Advisors and Automated Trading  MQL5 programming forum (2017) 
Prices you get from the terminal are already correct (normalized).

PIP, Point, or Tick are all different in general.
What is a TICK?  MQL4 programming forum (2014)
Hi amrali,
I read your post https://www.mql5.com/en/forum/440534 and i have to say "in a word" excellent. this is exactly the problem that I faced.
But also I think that, at least for me , it's not a cosmetic quetion becasue if you see this number in debugger it signifies that if you apply an arithmetic operation to this kind of number the digits count to the result.
so , as you said, in other languages that I use ( C# / Cpp ) and relative degugger this problem is not found.
what is still confusing me is that when i apply a function like NormalizeDouble(VolumeStep , 2); it seems that nothinig happens to the result. That's not good form me.
now : what is the next step ? I wold like to finish my EA for my daughter if any one has some suggestion is appreciate.
double VolumeStep = MarketInfo(symbol, SYMBOL_VOLUME_STEP);
Do not round the volume step, it is already rounded.
To round the lot volume to the symbol's volume step, use:
// the value of calculated lots double lots = xxxxx; // round down to symbo's volume step double VolumeStep = MarketInfo(symbol, SYMBOL_VOLUME_STEP); lots = MathFloor(lots / VolumeStep) * VolumeStep;
Hi Guys,
@William : thanks for remind me all this points about normlaization. something i already knew ,but is allways correct to be aware of.
@amrlai : also thank to you for the correct way of rounding.
a question ? . So you all are saying that even though a value that has been normalized and/or round ( suppose lots ) has number of digits like 4.6000000000000005 it doesn't matter when you put an order setting these value
TradeRequest.volume , TradeRequest.price, TradeRequest.sl, TradeRequest.tp with numer of digit thats seems wrong in the debugger ?
thank a lot guys
I tried to finish the EA and I start to test it in account demo. when I launched the EA i get these messages :
2023.03.24 09:29:16.461 Trades '1390720': failed market sell 74.1 XAUUSD sl: 1988.35 tp: 1928.69 [No money]
I am not able to read these numbers : sell 78.1 XAUUSD sl: 1988.35, tp: 1928.69  986.27, tp: 1928.69 [Invalid stops] ...what's does it mean ?
I mean comparing the sl: 1988.35 against sl: 1986.27 why they are [invalid stops] ??
could someone give me a sight and point me in the right direction ?
this is a code snippet for symbol = "AUXUSD"
int data = CopyRates(symbol, PERIOD_M5, 0, 2, rates); .. double lastLow = rates[1].low; // prices double lastHigh = rates[1].high; // prices .. entryPrice = rates[1].high; Ask = SymbolInfoDouble(symbol, SYMBOL_ASK); .. stopLoss = lastHigh + SymbolInfoDouble(symbol, SYMBOL_TRADE_TICK_SIZE); .. for (int i = PositionsTotal()  1; i >= 0; i) { ulong ticket = PositionGetTicket(i); if (PositionGetString(POSITION_SYMBOL) == symbol) { double currentPositionStopLoss = PositionGetDouble(POSITION_SL); double newPositionStopLoss; if (PositionGetInteger(POSITION_TYPE) == POSITION_TYPE_BUY) { newPositionStopLoss = PositionGetDouble(POSITION_PRICE_OPEN) + trailingStop * _Point; if (newPositionStopLoss > currentPositionStopLoss) { trade.PositionModify(ticket, newPositionStopLoss, PositionGetDouble(POSITION_TP)); } } else { newPositionStopLoss = PositionGetDouble(POSITION_PRICE_OPEN)  trailingStop * _Point; if (newPositionStopLoss < currentPositionStopLoss) { trade.PositionModify(ticket, newPositionStopLoss, PositionGetDouble(POSITION_TP)); } } } }
 Free trading apps
 Over 8,000 signals for copying
 Economic news for exploring financial markets
You agree to website policy and terms of use
Hi to all guys , I am new here,
recently while i was trying to code en EA and I noted that almost in any cases when i read values with a sample call like :
double VolumeStep = MarketInfo(symbol, SYMBOL_VOLUME_STEP); or
double MinVolume = MarketInfo(symbol, SYMBOL_VOLUME_MIN);
I get a strange value : 0.100000000000000006 instead of 0.01 as i expected
i tried to remove the last char with code like : VS1 = NormalizeDouble(VolumeStep , 2); but i still get the same value 0.100000000000000006
also tried to convert tostring with :
string VS = DoubleToString( VS1 , 2 ); and i get "0.01" then
VolumeStep = StringToDouble( VS); and get the same value = 0.100000000000000006
there is someone that can help me to get rid of this problem ? could it be my machine or the compiler or what else.
I have the last version of metaeditor installed ( version 5 build 3640 ) 17032023
thanks to all in advance
PS : I read some post about a similar problem but i didn't read any valid solution that solve this strange behaviour.