Python 2.7打印问题

Question

I'm making a program that will convert digital storage units. Like, you could ask it how many bits are in x amount of megabits. I'm just testing it with one if statement, but I CANNOT get it to print the answer.

import re

UNITS = ["bit", "byte", "exabit", "exabyte", "gigabit", "gigabyte", 
"kilobit", "kilobyte", "megabit", "megabyte", "petabit", "petabyte", 
"terabit", "terabyte"]

PLURAL_UNITS = ["bits", "bytes", "exabits", "exabytes", "gigabits", 
"gigabytes", "kilobits", "kilobytes", "megabits", "megabytes", "petabits", 
"petabytes", "terabits", "terabytes"]

PROMPT_1 = "How many "
PROMPT_2 = "are in "

def convert():
    first_unit = raw_input(PROMPT_1)
    second_unit = raw_input(PROMPT_2)

    number_of = re.findall('\d+', second_unit)

    number = number_of[0]

    if first_unit == PLURAL_UNITS[0] and second_unit == " " + PLURAL_UNITS[1]:
        answer = float(number)*8
        print(answer)


convert()

Answer 1

Look at this line:

if first_unit == PLURAL_UNITS[0] and second_unit == " " + PLURAL_UNITS[1]:

With this line your code will only print if the first input is "bits" and the second input is " bytes" . Inputting anything else makes the code under the if statement (which includes your print ) get skipped.

Answer 2

It doesn't print because it doesn't reach your print statement. One or both of your conditions of your if statement is False . To check which, print their results:

def convert():
    first_unit = raw_input(PROMPT_1)
    second_unit = raw_input(PROMPT_2)

    number_of = re.findall('\d+', second_unit)

    number = number_of[0]

    print('first check:', first_unit == PLURAL_UNITS[0])
    print('second check:', second_unit == " " + PLURAL_UNITS[1])
    if first_unit == PLURAL_UNITS[0] and second_unit == " " + PLURAL_UNITS[1]:
        answer = float(number)*8
        print(answer)


convert()

Answer 3

In python2, print is a statement, not a function. print answer