itaggedthisquestionasjavascriptbecauseeventhoughicurrentlywrotethisinpython，ifitwouldbeeasiertoimplementinjavascript，icoulicoulted
myassignmentistomakeasignificantfigurecalculationcheckerforthechemistrydepartment.whatthansisthestudenterstherstheirdardatment thewebappwillperformpredefinedoperationsontheirfieldsandkeeptrackofsignificantfiguresandseeeiftheiranswerhasthe
whenibroketheproblemdownintowhatifigureisagoodworkflow，irealizedthatiwouldneedawayforeitherpython (thebackendsincethisisawet or JavaScript (causeyoucouldalwaysvalidateitonthefrontendnoproblem ) )。 todeterminethenumberofsignificantdigits.ididalittleresearchandcameacrossthisquestionwhichtellsmethatineededtoworkwithpython ssthon rrentpythoncodefeelsalmostcomplete，butthereisstillonemajorchallengeiface
导入re
deffind_SIGfigs(x ) :
# changethe ' e ' tolowercaseifthestudenttypeditinasuppercase
x=x.lower ()
if(e ) inx ) :
mystr=x.split('e ' ) )。
# thisfunctionassumesthatthenumberontheleftofthe ' e ' is
# thenumberofsigfigs.thatwouldbetrueforuserinputbutnot
# truewhenpythonconvertsafloattoscientificnotation
returnlen((re.search('[0-9] '，myStr[0] ) ).group ) )
else:
# putitineformatandreturntheresultofthat
# # # problem : pythonmakesmehardcodethenumberofsigfigsas '2'
# # # without the2thereitalwaysdefaultsto 6
return find _ SIG figs (“%.* e“%”2，float(x ) x ) )
find_SIGfigs(1.3e-4 ) )
2
find_SIGfigs(1234 ) )。
3
find_SIGfigs(123456 ) )
3
find_SIGfigs(1.2345E3 ) )。
5
then without the 2
return find _ SIG figs (“%.e“%”float ) ) x ) )
# becauseitchangesitto 1.234000 e 3
find_SIGfigs(1234 ) )。
7
# becauseitchangesitto 1.234560 e 5
find_SIGfigs(123456 ) )
7
So simply put，myproblemisthatineedasimplewaytocountthesigfigswhenitisnotexplicitlydeclaredbythestudent . istheresomeeasywaythaticoulddropeveryzerobeforethe ' e ' untilitgetstothefirstnonzerodigit.I guess，inedtostartrtfromthebachebacachbactioromtiomthebactioractioromtinged
edit 3360 soafteralittlemorefiddling，ihopethisisanappropriatesolutiontotheproblem.itesteditseveraltimes，butnotorigorigousssses
deffind_SIGfigs(x ) :
“”returnsthenumberofsignificantdigitsinanumber.thistakesintoaccount
stringsformattedin 1.23 E3 formatandevenstringssuchas 123.450 ' '
# change all the 'E' to 'e '
x=x.lower ()
if(e ) inx ) :
# returnthelengthofthenumbersbeforethe ' e '
mystr=x.split('e ' ) )。
返回len (mystr [0]-1 # tocompenstateforthedecimalpoint
else:
# putitineformatandreturntheresultofthat
### NOTE: because of the 8 below，itmaydocrazythingswhenitparses9SIG figs
n='%.*e'%(8，float(x ) ) ) ).split('e ) ) ) )。
# removeandcountthenumberofremoveduseraddedzeroes.(thesearesigfigs )。
if '.' in x:
s=x.replace '.'，'')
#number of zeroes to add back in
L=len(s )-len (s.RS trip ) ) '0) )
# stripofthepythonaddedzeroesandaddbackintheonestheuseradded
n[0]=n[0].rstrip('0' ) '.join(['0'fornuminxrange(l ) ]
else:
# theuserhadnotrailingzeroessojuststripthemall
n[0]=n[0].RStrip('0) )。
# passitbacktothebeginningtobeparsed
returnfind_SIGfigs(e'.join () ) )
ithinkregularexpressionsareabitofanoverkillhere，butyourmethodshouldworkandi ' MSU reit ' snotaperformanceissue。
ithink you ' reontherighttrackwithwhatyoudescribeattheend.iwouldusesplit (' e ' ) followedbyRStrip ) '0)，whichwilllremove