Initial commit

numberwords.py

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+# numberwords.py
+# --------------
+# By MWC Contributors
+# Functions to print out a verbal representation of an integer.
+
+MAXIMUM = 1000000
+DIGIT_NAMES = [
+    "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"
+]
+TWEEN_AND_TEEN_NAMES = [
+    "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"
+]
+TENS_NAMES = [
+    "ten", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"
+]
+
+def int_under_1000000_to_str(number):
+    "Returns a textual representation of the number."
+    check_number_in_range(abs(number), 0, MAXIMUM)
+    if number < 1000:
+        return int_under_1000_to_str(number)
+    else:
+        thousands, hundreds = divide_with_remainder(number, 1000)
+        thousands_text = int_under_1000_to_str(thousands)
+        hundreds_text = int_under_1000_to_str(hundreds)
+        return thousands_text + " thousand " + hundreds_text
+        
+def int_under_1000_to_str(number):
+    "Returns a textual representation of the number"
+    check_number_in_range(number, 0, 1000)
+    if number < 100:
+        return int_under_100_to_str(number)
+    else:
+        hundreds, tens = divide_with_remainder(number, 100)
+        hundreds_text = int_under_10_to_str(hundreds)
+        tens_text = int_under_100_to_str(tens)
+        return hundreds_text + " hundred and " + tens_text
+
+def int_under_100_to_str(number):
+    check_number_in_range(number, 0, 100)
+    tens, ones = divide_with_remainder(number, 10)
+    if tens == 0:
+        return int_under_10_to_str(number)
+    elif tens == 1:
+        return TWEEN_AND_TEEN_NAMES[ones]
+    else:
+        return TENS_NAMES[tens] + '-' + int_under_10_to_str(ones)
+
+def int_under_10_to_str(number):
+    check_number_in_range(number, 0, 10)
+    return DIGIT_NAMES[number]
+
+def check_number_in_range(number, minimum, maximum):
+    """Checks whether a number is at least minimum and less than maximum. 
+    Raises an error if the number is not in range.
+    """
+    if number < minimum:
+        raise ValueError(f"{number} must not be below {minimum}.")
+    if number >= maximum:
+        raise ValueError(f"{number} must be less than {maximum}.")
+
+def divide_with_remainder(dividend, divisor):
+    """Divides one number by another, using whole-number division. 
+    Returns the quotient and the remainder.
+    Note how a function can return more than one value!
+    """
+    quotient = dividend // divisor
+    remainder = dividend % divisor
+    return quotient, remainder