(一)if 语句
if语句
people = 20
cats = 30
dogs = 15
if people < cats:
print("Too many cats,The world is doomed")
if people > cats:
print("Not mangy 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.")
运行的结果:
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.
[Finished in 1.4s]
上面有if代码块,if代码块创建了一个分支;按照python语法要求必须缩进4个空格,这是告诉python创建了新的代码块。如果添加上elif,else等。
Else和if
people = 30
cars =40
trucks = 15
if cars > people:
print("We should take the cars.")
elif cars < people:
print("We should not take the cars.")
else:
print("We cat't decide.")
if trucks >cars:
print("That too many trucks!")
elif trucks < cars:
print("Maybe we could take the trucks!")
else:
print("We still can't decide!")
if people > trucks:
print("Alright, let's just take the trucks.")
else:
print('Fine, let\'s stay home then')
运行的结果:
We should take the cars.
Maybe we could take the trucks!
Alright, let's just take the trucks.
[Finished in 132ms]
注意:if-elif-else语句,python从顶部开始,只运行第一个True的代码块,其他的就不运行了;所以如果需要每个条件都需要做出判断的情况下,可以使用多个if条件,像上面的多个if语句。
IF嵌套使用
print("""You enter a dark room with two doors.
Do you go through door #1 or door #2?""")
door = input(">")
if door =='1':
print("There's a giant bear here eating a cheese cake.")
print("What do you do?")
print("1,Take the cake.")
print("2,Scream at the bear.")
bear = input(">")
if bear =='1':
print("The bear eats your face off.Good job!")
elif bear =='2':
print("The bear eats your legs off.Good job!")
else:
print(f"Well,doing {bear} is probably better.")
print("Bear runs away.")
elif door=='2':
print("You stare into the endless abyss at Cthulhu's retina.")
print("1,Blueberries.")
print("2,Yellow jacket clothespins.")
print("3,Understanding revolvers yelling melodies.")
insanity = input(">")
if insanity =='1'or insanity =='2':
print("Your body survies powered by a mind of jello.")
print("Good job!")
else:
print("You stumble around and fall on a knife and die. Good job!")
运行的结果:
You enter a dark room with two doors.
Do you go through door #1 or door #2?
>1
There's a giant bear here eating a cheese cake.
What do you do?
1,Take the cake.
2,Scream at the bear.
>2
The bear eats your legs off.Good job!
sublime text无法完成交互,使用终端解决交互的问题。
(二)FOR语句
the_count = [1,2,3,4,5]
fruits = ['apples','oranges','pears','apricots']
change = [1,'pennies',2,'dimes',3,'quarters']
#this first kind of for-loop goes through a list
for number in the_count:
print(f"This is count {number}")
#same as above
for fruit in fruits:
print(f"A fruit of type {fruit}")
# also we can go through mixed lists too
# notice we have to use {} since we don't know what's in it
for i in change:
print(f"I got {i}")
#we can also build lists, first start with an empty one
elements = []
# then use the range function to do 0 to 5 counts
for i in range(0,6):
print(f"Adding {i} to the list.")
# append is a function that lists understand
elements.append(i)
# now we can print them out too
for i in elements:
print(f"Elements was: {i}")
运行的结果:
This is count 1
This is count 2
This is count 3
This is count 4
This is count 5
A fruit of type apples
A fruit of type oranges
A fruit of type pears
A fruit of type apricots
I got 1
I got pennies
I got 2
I got dimes
I got 3
I got quarters
Adding 0 to the list.
Adding 1 to the list.
Adding 2 to the list.
Adding 3 to the list.
Adding 4 to the list.
Adding 5 to the list.
Elements was: 0
Elements was: 1
Elements was: 2
Elements was: 3
Elements was: 4
Elements was: 5
[Finished in 116ms]
注意for 语句的遍历,以及函数range的用法,注意点。
(三)while语句
i = 0
numbers = []
while i < 6:
print(f"At the top i is {i} ")
numbers.append(i)
i +=1
print("Numbers now:",numbers)
print(f"At the bottom i is {i}")
print("The numbers:")
for i in numbers:
print(i)
运行的结果:
At the top i is 0
Numbers now: [0]
At the bottom i is 1
At the top i is 1
Numbers now: [0, 1]
At the bottom i is 2
At the top i is 2
Numbers now: [0, 1, 2]
At the bottom i is 3
At the top i is 3
Numbers now: [0, 1, 2, 3]
At the bottom i is 4
At the top i is 4
Numbers now: [0, 1, 2, 3, 4]
At the bottom i is 5
At the top i is 5
Numbers now: [0, 1, 2, 3, 4, 5]
At the bottom i is 6
The numbers:
0
1
2
3
4
5
[Finished in 133ms]
分支和函数
from sys import exit
def gold_room():
print("This room is full of gold. How much do you take?")
choice = input('>')
if '0' in choice or '1' in choice:
how_much = int(choice)
else:
dead("Man,learn to type a number.")
if how_much <50:
print("Nice,you're not greedy,you win!")
exit(0)
else:
dead("You greedy bastard!")
def bear_room():
print('There is a bear here.')
print("The bear has a bunch of honey.")
print("The fat bear is in front of another door.")
print("How are you going to move the bear?")
bear_moved =False
while True:
choice = input('>')
if choice =='take honey':
dead("The bear looks at you then slaps your face")
elif choice =="taunt bear" and not bear_moved:
print("The bear has moved from the door.")
print("You can go through it now.")
bear_moved = True
elif choice=="taunt bear" and bear_moved:
dead("The bear gets pissed off and chews your leg.")
elif choice=="open door" and bear_moved:
gold_room()
else:
print("I got no idea what that means.")
def cthulhu_room():
print("Here you see the great evil Cthulhu")
print("He,it,whatever strats at you and you go insane")
print("Do you flee your life or eat your head?")
choice = input(">")
if 'flee' in choice:
strat()
elif 'head' in choice:
dead("Well that was tasty!")
else:
cthulhu_room()
def dead():
print(why,"Good job!")
exit(0)
def start():
print("You are in a dark room.")
print("There is a door to your right and left.")
print("Which one do you take?")
choice = input('>')
if choice =='left':
bear_room()
elif choice =='right':
cthulhu_room()
else:
dead("You stumble around the room until you starve.")
start()
运行的结果:
You are in a dark room.
There is a door to your right and left.
Which one do you take?
>left
There is a bear here.
The bear has a bunch of honey.
The fat bear is in front of another door.
How are you going to move the bear?
>taunt bear
The bear has moved from the door.
You can go through it now.
>open door
This room is full of gold. How much do you take?
>1000
You greedy bastard! Good job!
理解这个游戏中的逻辑。