Using StringFormat to Truncate Float values

[millisys 0]

I have been experimenting with the StringFormat() function to limit the number of values after the decimal point without rounding.

For example truncating to 12.123456 to 12.12345 instead of 12.12346.

From the help file and experimenting, the 'e' and 'f' precision values round the last number. Does anyone know of a precision type that just removes any digits beyond the precision specified?

Also, I have written a _Truncate function using StringLeft(), StringInStr() and Number() but I am hoping it can also be done using an 'on-board' function such as StringFormat().

Thank you.

[PhoenixXL 159]

treat the float as a string and then convert it into a number

Code

;12.123456 to 12.12345
Local $int=12.123456
Local $_Formatted=Number(StringFormat('%.8s',$int))
ConsoleWrite($_Formatted&@CR)

[millisys 0]

hi phoenixxl,

thank you for your response.

that will work if the number before the decimal is always 2 digits. i am trying to retain 6 digits after the decimal point regardless of the length of the number before the decimal point. any ideas?

[PhoenixXL 159]

oh come on!

that u can figure out

Edit:

The code

;12.123456 to 12.12345
Local $int=1200.123456
MsgBox(0,'',_StringFormatDouble($int))

Func _StringFormatDouble($nDouble)
Local $nFloat=StringSplit($nDouble,'.',2)
$nFloat[0]=Number($nFloat[0])
Local $_Formatted=Number('0.'&StringFormat('%.5s',$nFloat[1]))
Return $nFloat[0]+$_Formatted
EndFunc

You can add the @error check

Regards

Phoenix XL

Edited September 15, 2012 by PhoenixXL

[guinness 1,458]

Local $nFloat = 12.123456
Local $iCount = 5
ConsoleWrite(StringRegExpReplace($nFloat, '(d*.d{' & $iCount & '})d*', '1') & @CRLF)

Edit: I like to use regular expressions as StringFormat can sometimes be a little slow and a regular expression is always good practice.

Edited September 15, 2012 by guinness

[millisys 0]

hi phoenixxl,

thank you.

i have been using a formula similar to that but was hoping to avoid using the stringsplit() function by using a StringFormat() precision type that did not round the last digit.

[guinness 1,458]

millisys,

I'm keen to see your _Truncate function.

[millisys 0]

hi guinness,

thank you. i would like to use a regexpreplace() but don't have much experience with it.

i tried the number 12.12999999 and it rounded to 12.13. I was hoping the formula would return 12.12999.

here is my function. it wouldn't surprise me if there is a flaw somewhere in it

Func _truncate($number,$places)
return number(stringleft($number,stringinstr($number,".")+$places))
EndFunc

[guinness 1,458]

i tried the number 12.12999999 and it rounded to 12.13. I was hoping the formula would return 12.12999.

Really as my example returned 12.12999. Try it again.

[guinness 1,458]

Working example of your function _Truncate.

Local $nFloat = 12.12999999
Local $iCount = 5
ConsoleWrite(_Truncate($nFloat, $iCount) & @CRLF)

Func _Truncate($vNumber, $iPlaces)
    Return Number(StringRegExpReplace($vNumber, '(d*.d{' & $iPlaces & '})d*', '1'))
EndFunc   ;==>_truncate

Edited September 15, 2012 by guinness

[millisys 0]

hi guinness,

can you please try the number 55645612.12999999?

[guinness 1,458]

hi guinness,

can you please try the number 55645612.12999999?

The problem isn't the SRE but converting a float to a string.

ConsoleWrite(String(55645612.12999999) & @CRLF)

[millisys 0]

hi guinness,

i agree. how do i get the number 55645612.12999999 to truncate down to 55645612.12999?

[guinness 1,458]

That's the question I can't answer I'm afraid, it's a limitation of some degree.

[millisys 0]

hi guinness,

from the tests i have run the goofy little function that i wrote seems to work. is there a number that it won't truncate properly?

[guinness 1,458]

hi guinness,

from the tests i have run the goofy little function that i wrote seems to work. is there a number that it won't truncate properly?

55645612.12999999!!! So I can't see how either one of ours is better? Both provide exactly the same output but by a different means. Edited September 15, 2012 by guinness

[guinness 1,458]

Also why not do some tests?

Local $vRandom = 0
For $i = 0 To 100
    $vRandom = Random(0, 999999999)
    ConsoleWrite($vRandom & ' >> ' & _Truncate($vRandom, 5) & @CRLF)
NExt

Func _Truncate($vNumber, $iPlaces)
    Return Number(StringRegExpReplace($vNumber, '(d*.d{' & $iPlaces & '})d*', '1'))
EndFunc   ;==>_Truncate

[millisys 0]

hi guinness,

yikes! that is weird. are there programming languages that are able to handle floats?

[guinness 1,458]

Google around and you will see the issue isn't limited to just AutoIt.

[millisys 0]

guinness,

i will play around with this. it seems like splitting it before and after the decimal has possibilities and working with integers. i imagine that it is the combining of the numbers that will cause the numbers to change again.

thanks for your help