判断条件

输入年龄，根据年龄条件判断符合与否

age = 20
if age >= 18:
    print ('your age is:',age)
    print ('adult')

your age is: 20
adult

根据python的缩进规则及if语句的中的判断条件，使用else,如下

age = 15
if age >= 18:
    print ('your age is:',age)
    print ('adult')
else:
    print ('your age is:',age)
    print ('teenager')

your age is: 15
teenager

使用elfi语句做判断

age = 3
if age >= 18:
    print ('adult')
elif age >= 6:
    print ('teenager')
else:
    print ('kid')

kid

• input的使用

birth = input('birth:')
if birth < 2000:
    print ('00前')
else:
    print ('00后')

birth:1988



---------------------------------------------------------------------------

TypeError                                 Traceback (most recent call last)

<ipython-input-14-e5b461b8929a> in <module>()
      1 birth = input('birth:')
----> 2 if birth < 2000:
      3     print ('00前')
      4 else:
      5     print ('00后')


TypeError: '<' not supported between instances of 'str' and 'int'

birth值为str,字符类型无法对比，只有转换成数字类型才可以对比

s = input('birth:')
birth = int(s)
if birth < 2000:
    print ('00前')
else:
    print ('00后')

birth:1999
00前

s = input('birth:')
birth = int(s)
if birth < 2000:
    print ('00前')
else:
    print ('00后')

birth:abc



---------------------------------------------------------------------------

ValueError                                Traceback (most recent call last)

<ipython-input-16-69188189e7f4> in <module>()
      1 s = input('birth:')
----> 2 birth = int(s)
      3 if birth < 2000:
      4     print ('00前')
      5 else:


ValueError: invalid literal for int() with base 10: 'abc'