accumulate - VB.NET - Accumulating Numbers and Calculating Average -

i have started on , working intended except 2 of accumulating totals, calculation not working way need to. instead of adding previous sales total tacks new sale on end...

for example: input 1 snowboard , 1 snowboard boots, works, 1 shown in summary both snowboards , snowboards boots. when try input again in order keep running total of sales have problem, enter 1 snowboard , 1 snowboard boots, , summaries show 11 rather 2. why happen?

   ' declare module-level variables , constants. private snowboardssold, bootssold, salecount integer private itemssold integer private totalsales decimal const snowboard_rate decimal = 20d const boots_rate decimal = 30d   private sub calculatebutton_click(byval sender system.object, byval e system.eventargs) handles calculatebutton.click     ' calculate prices     dim snowboards, boots integer     dim snowboardsale, bootssale, thissale, averagesalesever decimal      try         ' convert snowboard input numeric variable.         snowboards = integer.parse(snowboardstextbox.text)          try             ' convert boots if snowboard successful.             boots = integer.parse(withbootstextbox.text)             ' calculate values sale.             snowboardsale = snowboards * snowboard_rate             bootssale = boots * boots_rate             thissale = snowboardsale + bootssale              ' calculate summary values.             totalsales += thissale             bootssold += bootssale             snowboardssold += snowboardsale             salecount += 1             averagesalesever = totalsales / salecount              ' format , display prices sale.             snowboardspricetextbox.text = snowboardsale.tostring("c")             bootspricetextbox.text = bootssale.tostring("c")             totalpricetextbox.text = thissale.tostring("c")              ' format , display values summary.             snowboardrentaltextbox.text += snowboards.tostring()             bootsrentaltextbox.text += boots.tostring()             totalchargestextbox.text = totalsales.tostring("c")             averagechargetextbox.text = averagesalesever.tostring("c")          catch bootsexception formatexception             ' handle boots exception.             messagebox.show("please enter numbers.", "data entry error",                             messageboxbuttons.ok, messageboxicon.error)             withbootstextbox                 .focus()                 .selectall()             end         end try      catch snowboardsexception formatexception         ' handle snowboard exception.         messagebox.show("please enter numbers.", "data entry error",                         messageboxbuttons.ok, messageboxicon.error)         snowboardstextbox             .focus()             .selectall()         end      catch anexception exception         'handle other exception.         messagebox.show("error: " & anexception.message)     end try end sub 

first, might want change way grab numbers:

'convert snowboard input value numeric variable. snowboardinteger = integer.parse(snowboardstextbox.text) 

to:

dim snowboardinteger integer if tryparse.integer(snowboardstextbox.text, snowboardinteger) = false  ' if parses, snowboardinteger have value,   'else function returns false      messagebox.show("please enter numbers") end if 

also, parsing textboxes twice. once in declaration right after. doesnt right:

snowboardsalecountinteger += 1 withbootssalecountinteger += 1 totalsalecountinteger += totalchargessuminteger   ' ????? averagechargeinteger = totalchargessuminteger / totalsalecountinteger 

adding 'charges' 'counter' doesnt seem right. if want avg shouldnt be:

totalsalecountinteger = snowboardsalecountinteger + withbootssalecountinteger  

if want fractions such 'xx.yy' in result, averagechargeinteger should double or decimal, unless whole dollars ok assignment.

if need accumulate previous clicks, need move declarations out of procedure snowboardsuminteger, withbootssuminteger can accumulate. is, withbootssalecountinteger, totalsalecountinteger dont , 1. wonder if 'salecounter' shouldnt increase value in textbox rather 1 (dont have assignment in front of me).

one more thing might need here:

snowboardpriceinteger = snowboardinteger * snowboard_rental_rate withbootspriceinteger = withbootsinteger * with_boots_rental_rate totalpriceinteger = snowboardpriceinteger + withbootspriceinteger 

your constants decimal (snowboard_rental_rate) so, result of calc has go decimal var, snowboardpriceinteger , other not. integer cannot store fractional result multiplication or division.

something like:

' sales accumulators  private totalsales decimal = 0  private itemssold integer = 0 

click event:

' sale: dim snowboards integer  dim boots integer  ' values text boxes, then: dim snowboardsale decimal = (snowboards * snowboardrate) dim bootssale decimal = (boots * bootsrate) dim thissale decimal =  snowboardsale  + bootssale    ' update accumulators totalsales += thissale itemssold += (boots + snowboards)  ' calc average dim averagesalesever decimal = totalsales  / itemssold   ' display results in textboxes '(this exercise left student  ;)  ) 

hth

i think confused many variables , ones left on old attempts.