integer_to_string_problem.py

# Integer -> String
# 1 to 999999999

#create global dictionaries of specific "number" words
onesDic = {"1": "one ", "2": "two ", "3": "three ", "4": "four ", "5": "five ", "6": "six ", "7": "seven ", "8": "eight ", "9": "nine "}
teensDic = {"0": "ten ", "1": "eleven ", "2": "twelve ", "3": "thirteen ", "4":"fourteen ", "5":"fifteen ", "6":"sixteen ", "7":"seventeen ", "8":"eighteen ", "9": "nineteen "}
entysDic ={"2":"twenty ", "3": "thirty ", "4": "forty ", "5":"fifty ", "6":"sixty ", "7":"seventy ", "8":"eighty ", "9": "ninety "}

def int_to_string(num):
    numString = str(num)
    numLength = len(numString)
    resultString = ""
    teensFlag = False # A flag to signal when to use the "teen" words
    skipThousands = False # A flag to signal when the word "thousand" gets skipped in colloquial English
    for index, letter in enumerate(numString):
        newIndex = numLength - index - 1 # A new index which allows us to parse the word left-to-right
        if newIndex % 3 == 0: # retrieve ones place 
            if teensFlag == True:
                resultString += teensDic[letter]
                teensFlag = False
            elif letter != "0":
                resultString += onesDic[letter]
        if newIndex % 3 == 1: # retrieve tenths place
            if letter == "1":
                teensFlag = True
            elif letter != "0":
                resultString += entysDic[letter] 
        if newIndex % 3 == 2: # retrieve hundredths place
            if letter != "0":
                resultString += onesDic[letter] + "hundred "
                
        if newIndex == 3 and not skipThousands: # use word "thousand"
            resultString += "thousand "
        if newIndex == 6 and newIndex != 0: # use word "million"
            resultString += "million "
            if numString[3:6] == "000":
                skipThousands = True
        
    return resultString
        

testArray = [1, 7, 14, 86, 111, 123, 800, 702, 90134, 18001, 12015, 7790134, 11000000, 84000000, 100000000, 401019710, 876543210, 999999999]
for num in testArray:
    print int_to_string(num)