Is there a bug?

[marcelo.linhaverde]

Hello. Good afternoon.

For years, I've encountered an unusual situation when comparing variables with zero. I build a simple example with specific values:

function main()
local a
local e

a:={-405.97,135.00,135.00,135.97}
e:=0
aeval( a,{|i| e+=i } )

? transform( e,"99999.99")

if e<0
? "Negative"
endif
if e>0
? "Positive"
endif
if e==0
? "Zero"
endif

return( nIL )

The code above displays:

0.00
Negative

The order of the values in the array affects the final result. Seems crazy!

My build: Harbour 3.2.0dev (r2410180556)

Can anyone help?

[José M. C. Quintas]

operation with float point.

confirm using anything like this 

? e / 1.00000000000000000000000000000000000000

possible workaround on operation and/or result

e := val(str(e,2))

May be you have same problem using double on mysql, but not on currency or decimal.

José M. C. Quintas

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[Mario H. Sabado]

Hi,

Displaying the result of e from your sample with higher decimal precision.

? transform(e,"999.999999999999999999999")  

 -0.000000000000028421709

You may need to use Round() function to achieve the result you expected.

Regards,

Mario
















. 

--

[Jose Carlos da Rocha Rocha]

Hi friends,

ZERO is not a positive on negative number. ZERO is ZERO.

In my very old Harbour Compiler Alpha build 45.0 (Flex) Copyright 1999-2005, http://www.harbour-project.org/

I tested this same code and the result was the same. 0 and Negative.

Try this code and be shocked

function main()
local a
local e

a:={-405.97,135.00,135.00,135.97}
e:=0
aeval( a,{|i| e+=i } )

? transform( e,"99999.999999999999999999999999")

if e<0
   ? "Negative"
endif
if e>0
   ? "Positive"
endif

if e=0.00

   ? "Zero"
endif

return( nIL )

[Marek Długosz]

I use conversion to whole numbers by *100 and divide after calcuations
or keep error of rounding in check:
e:=0
aeval({1/3,1/3,1/3},{lxle:=x-(x:=round(x+e,2)),qout(tran(x,"9.99"))})

31 lip 2025 06:55:13 Jose Carlos da Rocha Rocha <5vol...@gmail.com>:

To view this discussion visit https://groups.google.com/d/msgid/harbour-devel/b074199a-1dde-4151-b084-fb60bf4f7033n%40googlegroups.com.

[frank van nuffel]

Hi,

(i haven't tested) but what about comparing to 0.00 instead of to 0?

regards, lohen

Op woensdag 30 juli 2025 om 19:15:51 UTC+2 schreef marcelo.linhaverde:

[Alex Strickland]

Hi

Numbers are stored as floating point (double, float) in Harbour (and Clippre) but these issues affect all languages that use them. You will find many many articles explaining the problem. Rounding is all you can do.

All programmers should know this but I managed to get a computer science degree without being made aware of it :)

--

Regards

Alex

[marcelo.linhaverde]

Hi. This workaround works very well.

#xcommand DEFAULT <v1> TO <x1> [, <vn> TO <xn> ] => ;
                                IF <v1> == NIL ; <v1> := <x1> ; END ;
                                [; IF <vn> == NIL ; <vn> := <xn> ; END ]

function IsNegativo( n,nDec )
   local j

DEFAULT nDec TO   set( _SET_DECIMALS)

   j := -1* ( 10^(-nDec ) )

return( n <= j )

function IsPositivo( n, nDec )
local j

DEFAULT nDec TO   set( _SET_DECIMALS)

j :=  10^(-nDec )

return( n >= j )

function IsZero( n,nDec )

DEFAULT nDec TO   set( _SET_DECIMALS)

   return( !( IsNegativo( n, nDec ) .or. IsPositivo( n, nDec ) ) )

But, I have a huge code.

 Is there a away do a "translate" IP statetent ou replace if() function? Sugestions?

Thanks for all anwsers.

Marcelo G Tavares

[José M. C. Quintas]

AEval( a, { | i | e := Val(Str( e + i, 15,2)) }

or at the end

e := Val( Str( e, 15, 2 ))

On this way, you do not need extra functions.

José M. C. Quintas

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