EXPOSURE VALUE CALCULATOR PRO PYTHON

import math
import os

def calculate (ev1, av2):
  ev2 = float(math.log(pow(av2,2),2))
  rst = float(ev1 - ev2)
  if rst < 0:
      rst = float(abs(rst))
  result = float(pow(2,rst))
  return result

def check(stringa):
  c = 0
  i = 0
  while i < len(stringa):
      car = stringa[i:i+1]

      if car == "0":
    c = c + 1
      if car == "1":
    c = c + 1
      if car == "2":
    c = c + 1
      if car == "3":
    c = c + 1
      if car == "4":
    c = c + 1
      if car == "5":
    c = c + 1
      if car == "6":
    c = c + 1
      if car == "7":
    c = c + 1
      if car == "8":
    c = c + 1
      if car == "9":
    c = c + 1
      if car == ".":
    c = c + 1
      i = i + 1


  if c == len(stringa):
    return True
  if c <> len(stringa):
    return False


def converti(tempo):
  if tempo > 3600:
    ore = int(tempo / 3600)
    temporest = tempo - (ore * 3600)
    minute = int(temporest / 60)
    sec = tempo - ((ore * 3600) + (minute * 60))
    result = str(ore) + "h" + str(minute) + "m" + str(sec) + "s"
    return result


  if tempo < 3600:
    minute = int(tempo / 60)
    sec = tempo - (minute * 60)
    result = str(minute) + "m" + str(sec) + "s"
    return result





global dia
global tempo1
global num
global den
global av1
global av2
global temp1
global strnum
global strden
global switch
global ev2a,ev2b
global ev2ai,ev2bi
global ev1i
global result


dia = [1,1.2,1.4,1.7,1.8,2,2.4,2.8,3.3,3.4,4,4.8,5.6,6.7,8,9.5,11,13,16,19,22]
os.system('clear')
switch = False
av1 = input("Diaframma a tutta apertura: ")
temp1 = raw_input("Tempo a tutta apertura: ")
if len(temp1) < 1: exit()
if av1 < 0: exit()
if temp1[len(temp1)-1:len(temp1)] == ".": exit()
if temp1[len(temp1)-1:len(temp1)] == "/": exit()
temp1 = temp1.replace("//", "/")
i = 0
while i < len(temp1):
  i = i + 1
  if temp1[i:i+1] == "/":
    switch = True
    strnum = temp1[0:i]
    strden = temp1[i+1:len(temp1)]
    if check(strnum) == False:
      exit()
    if check(strden) == False:
      exit()
    num = float(strnum)
    den = float(strden)



if switch == True:
   tempo1 = num / den
   ev1 = (pow(av1,2)) / tempo1
   ev1 = math.log(ev1,2)
   ev1i = int(ev1)
   print "EV: " + str(ev1)
   print ""
   for i in range(len(dia)):
     av2 = dia[i]

     if av2 <> av1:
    tempo2 = calculate(ev1,av2)
    ev2a = (pow(av2,2)) / tempo2
    ev2a = math.log(ev2a,2)
    ev2ai = int(ev2a)
    ev2b = (pow(av2,2)) / (1/tempo2)
    ev2b = math.log(ev2b,2)
    ev2bi = int(ev2b)

    if ev2ai == ev1i:
      print str(tempo2) + " sec @" + str(av2) + "   EV: " + str(ev2a)
    else:
      if tempo2 < 2:
          tempo2 = 1 / tempo2
          print str(tempo2) + " sec @" + str(av2) + "   EV: " + str(ev2b)
      else:
          print "1/" + str(tempo2) + " sec @" + str(av2) + "   EV: " + str(ev2b)




if switch == False:
   if check(temp1) == False:
     exit()

   tempo1 = float(temp1)
   ev1 = (pow(av1,2)) / tempo1
   ev1 = math.log(ev1,2)
   ev1ai = int(ev1)
   print "EV: " + str(ev1)
   print ""

   for i in range(len(dia)):
      av2 = dia[i]
      if av2 <> av1:
      tempo2 = calculate(ev1,av2)
      ev2a = (pow(av2,2)) / tempo2
      ev2a = math.log(ev2a,2)
      ev2ai = int(ev2a)
      ev2b = (pow(av2,2)) / (1/tempo2)
      ev2b = math.log(ev2b,2)
      ev2bi = int(ev2b)

      if ev2ai == ev1ai:
        if tempo2 < 60:
          print str(tempo2) + " sec @" + str(av2) + "   EV: " + str(ev2a)
        else:
          result = converti(tempo2)
          print result + " @" + str(av2) + "   EV: " + str(ev2a)
      if ev2bi == ev1ai:
        print "1/" + str(tempo2) + " sec @" + str(av2) + "   EV: " + str(ev2b)






print ""