1.IF语句
people=20
cats=30
dogs=15
if people<cats:
print("too many cats")
if people<dogs:
print("too many dogs")
else:
print("the world doesn't have so many dogs")
else:
print("cats are not so much, the world is normal")
print('-'*20)
dogs +=15
people+=15
if people<cats:
print("too many cats")
else:
print("cats are not so much, the world is normal")
if people<dogs:
print("too many dogs")
else:
print("the world doesn't have so many dogs")
too many cats
the world doesn't have so many dogs
--------------------
cats are not so much, the world is normal
the world doesn't have so many dogs
if对下面的代码起条件判断的作用
people=30
cars=40
trucks=15
if cars>people:
print("we should take cars")
elif cars==people:
print("we can't decide")
else:
print("we should not take cars")
we should take cars
if嵌套使用：
# 分数评级
score=int(input("请输入您的分数："))
if score>=90:
print("your grade is : A")
elif score>=80:
print("your grade is : B")
elif score>=70:
print("your grade is : C")
elif score>=60:
print("your grade is : D")
else:
print("your grade is : E")
请输入您的分数：88
your grade is : B
2.For语句
L=[]
def my_func(x):
return 2*x
for i in range(5):
L.append(my_func(i)) #对序列L依次增加0，2，4，6，8
L
[0, 2, 4, 6, 8]
[my_func(i) for i in range(5)] #列表推导式
[0, 2, 4, 6, 8]
3.while语句
i=0
numbers=[]
while i <6:
print(f"at the top i is {i}") #打印每一步循环中i的值
numbers.append(i) #将i的值依次添加到列表numbers
i +=1
print(f"numbers now is : {numbers}")
print(f"at the bottom i is {i}")
print("="*20)
print(f"the numbers:{numbers}")
for num in numbers:
print(num)
at the top i is 0
numbers now is : [0]
at the bottom i is 1
====================
at the top i is 1
numbers now is : [0, 1]
at the bottom i is 2
====================
at the top i is 2
numbers now is : [0, 1, 2]
at the bottom i is 3
====================
at the top i is 3
numbers now is : [0, 1, 2, 3]
at the bottom i is 4
====================
at the top i is 4
numbers now is : [0, 1, 2, 3, 4]
at the bottom i is 5
====================
at the top i is 5
numbers now is : [0, 1, 2, 3, 4, 5]
at the bottom i is 6
====================
the numbers:[0, 1, 2, 3, 4, 5]
0
1
2
3
4
5
def generate_list(n): #定义一个输入数字n，输出0-n之间（不含n）的列表
list=[]
i=0 #注意要定义i的初始值
while i<n:
list.append(i)
i +=1
return list
generate_list(6)
[0, 1, 2, 3, 4, 5]
generate_list(10)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
改变增加的值
def generate_list(n): #定义一个输入数字n，输出0-n之间（不含n）的列表
list=[]
i=0 #注意要定义i的初始值
while i<n:
list.append(i)
i +=2 #改变增加的值
return list
generate_list(20)
[0, 2, 4, 6, 8, 10, 12, 14, 16, 18]
用FOR循环写：
def generate_list2(n):
list=[]
for i in range(n):
list.append(i)
return list
generate_list2(6)
[0, 1, 2, 3, 4, 5]
用FOR循环不需要中间的增加值
for和while的区别是什么？
for循环只能迭代循环一些东西的集合，while能迭代循环任何类型的东西。但for更简洁通用。
分支和函数
from sys import exit
def dead(why):
print(why,"good job")
exit(0)
def gold_room():
print("this room is full of gold. how much would like to take ?")
choice=input("please input your choice: ")
if "0" or "1" in choice:
how_much=int(choice)
else:
dead("man, learn to type a number.") # dead是什么？后面定义的一个函数
if how_much<50:
print("nice, you are not greedy,you win")
exit(0)
else:
dead("you greedy bastard")
def bear_room():
print("there is a bear here.\n the bear has a bunch of honey.\n the fat bear is in front of another door.\n how are you going to move the bear?")
bear_moved=False
while True:
choice=input("please input your choice: ")
if choice == "take money":
dead("the bear looks at you the slaps your face...")
elif choice=="taunt bear" or bear_moved:
print("the bear has moved from the door.\n you can go through it now.")
bear_moved=True
elif choice =="open door" or bear_moved:
gold_room()
else:
print("I got no idea what that means.")
def cthu_room():
print("here you see that great evil clutlhu.")
print("he,it,whether stares at your life or eat your head ?")
choice=input("please input: ")
if "flee" in choice:
start()
elif "head" in choice:
dead("well that's tasty!")
else:
cthu_room()
def start():
print("you are in a dark room.\n there is a door to your left and right\n which one would you like to open?")
choice=input("please input: ")
if choice=="left":
bear_room()
elif choice=="right":
cthu_room()
else:
dead("you stumble around the room untill you starve.")
start()
you are in a dark room.
there is a door to your left and right
which one would you like to open?
please input: 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?
please input your choice: open door
this room is full of gold. how much would like to take ?
please input your choice: 1
nice, you are not greedy,you win
An exception has occurred, use %tb to see the full traceback.
SystemExit: 0
C:\ProgramData\Anaconda3\lib\site-packages\IPython\core\interactiveshell.py:3351: UserWarning: To exit: use 'exit', 'quit', or Ctrl-D.
warn("To exit: use 'exit', 'quit', or Ctrl-D.", stacklevel=1)
