Python中的if、else、elif语句用法简明讲解

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." 

root@he-desktop:~/mystuff# 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.

people = 30 
cars = 40 
buses = 15 
 
 
if cars > people: 
  print "We should take the cars." 
elif cars < people: 
  print "We should not take the cars." 
else: 
  print "We can't dicide." 
 
 
if buses > cars: 
  print "That's too many buses." 
elif buses < cars: 
  print "Maybe we could take the buses." 
else: 
  print "We still can't decide." 
 
 
if people > buses: 
  print "Alright, let's just take the buses." 
else: 
  print "Fine, let's stay home then." 

root@he-desktop:~/mystuff# python ex30.py 

We should take the cars.
Maybe we could take the buses.
Alright, let's just take the buses.