习题 29: 如果(if)
在文本编辑器中，编辑以下内容并保存到ex29.py文件中，同时在终端中运行该文件：
people = 20
cats = 30
dogs = 15
if people < cats:
print "Too many cats! The world is doomed!"
if people > cats:
print "Not many cats! The world is saved!"
if people < dogs:
print "The world is drooled on!"
if people > dogs:
print "The world is dry!"
dogs += 5
if people >= dogs:
print "People are greater than or equal to dogs."
if people <= dogs:
print "People are less than or equal to dogs!"
if people == dogs:
print "people are dogs."
执行结果：
$ python ex29.py
Too many cats! The world is doomed!
The world is dry!
People are greater than or equal to dogs.
People are less than or equal to dogs!
people are dogs.
