Why not then simply use floats?Rook Zimbabwe wrote:But... are not all currencies decimal to two places???
X.XX in whatever format?
Because they are inaccurate. The currency type is usually implemented as a 64-bit integer that is scaled so the last two digits represents decimal places. That way there won't be float inaccuracies.Why not then simply use floats?
IIRC doubles can be used for representing currency values. Not sure if it is as inaccurate as floats.Trond wrote:Because they are inaccurate. The currency type is usually implemented as a 64-bit integer that is scaled so the last two digits represents decimal places. That way there won't be float inaccuracies.Why not then simply use floats?
In storage, yes. In maths? I am sure you are right, but I need to have it explained.Trond wrote:Double is more accurate than floats, but integers are 100% accurate.
33 stored in an integer is exactly 33, but 33.3333 stored in a floating point variable isn't exactly 33.3333 but something close. So not 100% accurate.Integer 100 divided by 3 = 33
FP (single or double) 100 divided by 3 = 33.333' (with a few bits of imprecision in the 1/10000 or onwards mark).
Code: Select all
a.f = 100000001.0
Debug a - 100000000.0Code: Select all
b.d = 100000000000000001.0
Debug b - 100000000000000000.0
) for finance companies could deal with heavy duty reports for govt (and their scientific calculator wielding scrutineers). It could calculate interest, projections, rule of 72 and etc to the day (or hour if needs be) for thousands of clients with millions of dollars involved in some accounts. And not get the govt on the lender's (and therefore my) back.Code: Select all
Procedure.s x_strex(var.l,format.s) ; convert int to string using a format field, format characters space and -+#.#
Protected s.s, fl.l, sl.l, *f.CHAR, *s.CHAR, p.l, sb.l
;
; *** format integer to string
;
; in: var.l - int var
; f.s - format
; out: .s - string
;
; convert int var to string using a pattern
;
; pattern elements:
;
; '#' - number or leading zero
; ' ' - space, number or (when there's no '+' or '-' used in the format) sign
; '+' - positive or negative indicator
; '.' - decimal sign
;
; examples:
;
; x_strex( 1234, "###") = "***"
; x_strex( 1234, "##.##") = "12.34"
; x_strex(-1234, "##.##") = "*****"
; x_strex( 1, ".#####") = ".00001"
; x_strex( -1, "+ .##") = "- .01"
;
fl = Len(format)
s = Str(var)
sl = Len(s)
;
*f.CHAR = @format+fl*#Charsize ; using two pointers and two counters
*s.CHAR = @s+sl*#Charsize ; *f and *s are the pointers, fl and sl are the counters
;
If PeekC(@format) = '+' ; remember if there is a sign in a fixed place
p = 2
ElseIf PeekC(@format) = '-'
p = 1
Else
p = 0
EndIf
;
While fl > 0
fl = fl-1
*f = *f-#Charsize ; we could be in unicode mode...
If *f\c = '.' ; skip a dot if we pass one
Else
sl = sl-1
If sl >= 0
*s = *s-#Charsize
sb = *s\c ; sb contains the digit, AND is used as a flag
EndIf
Select *f\c
Case '-' ; ah, a sign in a fixed place
If sb = '-'
sb = -1 ; if sb = -1 we've managed to store the sign
Else
*f\c = ' '
EndIf
Case '+' ; same thing for the +
If sb = '-'
*f\c = sb
sb = -1
EndIf
Case '#' ; if we have data that is not a sign we're gonna fill it in
If sb = '-' Or sl < 0
*f\c = '0' ; otherwise it's going to be a zero
Else
*f\c = *s\c
EndIf
Case ' ' ; if there is no fixed spot for a sign we'll store the minus
If sb = '-' ; immediately on the first space we encounter
If p = 0
*f\c = '-'
sb = -1
EndIf
ElseIf sb <> -1 And sl >= 0 ; otherwise we'll just gonna fil it in
*f\c = *s\c
EndIf
EndSelect
EndIf
Wend
;
If sb = '-' Or sl > 0 ; if the sign wasn't stored or there was some data left
format = LSet("",Len(format),"*") ; we'll put in some stars to indicate overflow
EndIf
;
ProcedureReturn format
EndProcedure