如何将raw_input()与while循环一起使用

Question

只是尝试编写一个程序,将用户输入并将其添加到列表'数字':

print "Going to test my knowledge here"
print "Enter a number between 1 and 20:"

i = raw_input('>> ')
numbers = []

while 1 <= i <= 20 :
    print "Ok adding %d to numbers set: " % i 
    numbers.append(i)

    print "Okay the numbers set is now: " , numbers

但是,当我执行程序时,它只运行到raw_input()

Going to test my knowledge here
Enter a number between 1 and 20:
>>> 4

我在这里缺少一些基本规则吗？

Answer 1

raw_input 返回一个字符串而不是整数:

所以,

>>> 1 <= "4" <= 20
False

用途int():

i = int(raw_input('>> '))

if如果您只是从用户那里获取一个输入,请使用just :

if 1 <= i <= 20 :
    print "Ok adding %d to numbers set: " % i 
    numbers.append(i)

    print "Okay the numbers set is now: " , numbers

使用while多输入:

i = int(raw_input('>> '))
numbers = []

while 1 <= i <= 20 :
    print "Ok adding %d to numbers set: " % i 
    numbers.append(i)
    i = int(raw_input('>> '))                   #asks for input again
print "Okay the numbers set is now: " , numbers