笨办法学python习题31-40

习题31：作出决定
代码展示

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 lege 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 survives powered by a mind of jello.")
        print("Good job!")
    else:
        print("The insanity  rots your eyes into a pool of muck.")
        print("Good job!")

else:
    print("You stumble around and fall on a knife and die.Good job!")

运行截图

定义一个变量，用来记录用户的输入结果，依据变量值来判断if语句的分支选择：bear = input("> ")（注：》只是用户来提示用户输入，非必要存在）

习题32：循环和列表
代码展示

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"Element was:{i}")

运行截图

菜鸟教程for循环
菜鸟教程range函数
range()函数能够创建一整个函数列表，一般用在for循环当中。
函数语法：range(start,stop[,step])
start:计数是从start开始，一般默认为0。eg：range(5)等价于range(0,5)
stop:计数到stop结束，但不包括stop。eg：range(0，5)创建列表为[1,2,3,4]
step:步长，默认为1，eg：range(0，5)= range(0，5，1)

• range函数为创建一个列表，直接将range函数创建的列表赋值给elements[]而不通过for循环赋值是否可行？，修改代码为elements = range(0,6)，重新运行此函数得到了与之前相同的输出

菜鸟教程-列表
列表的数据项不需要具有相同的类型，访问列表中的值通过索引实现，列表索引从0开始

for循环开始时循环变量就被定义了，每次循环到它的时候，它都被重新初始化为当前循环中的元素值

elements.append()函数的功能时在列表尾部追加元素

习题33：while循环
代码展示

i = 0
numbers = []

while i < 6:
print(f"At the top i is {i}.")
numbers.append(i)

i = i+1
print("Number now:",numbers)
print(f"At the bottom i is {i}.")

print("The numbers:")

for num in numbers:
print(num)

运行截图
![](https://img2020.cnblogs.com/blog/2173005/202011/2173005-20201112212322462-1180906629.png)
用for循环改写while循环

i = 0
numbers = []
elements = range(0,6)
for j in elements:
print(f"At the top i is {i}.")
numbers.append(i)

i = i+1
print("Numbers now = ",numbers)
print(f"At the bottom i is {i}.")

print("The numberd")
for m in numbers:
print(m)

习题35：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 your number!")

    if how_much<50:
        print("Nicec,you're not greedy,ypu win!")
        exit(0)
    else:
        dead("You greedy bastard!")


def bear_room():
    print("There is a bear.")
    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 off.")
        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 off.")
        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 stars at you and you go insane.")
    print("Do you flee for you life or eat your head?")

    choice = input("> ")

    if "flee" in choice:
        start()
    elif "head" in choice:
        dead("Well that was tasty!")
    else:
        cthulhu_room()

def dead(why):
    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 == "right":
        cthulhu_room()
    elif choice == "left":
        bear_room()
    else:
        dead("You stumble around the room until you starve.")

start()

运行截图：

input函数的参数是一个将被打印出来的字符，通常用来提示用户输入
exit(0)可以用来终止某个程序，而其中的数字则用来表示是否是遇到错误而终止的，exit(1)通常表示程序发生了错误，而exit(0)则表示程序是正常退出的

习题38：列表的操作
代码展示

ten_things = "Apples Oranges Crows Telephone Light Sugar"
print("Wait there not 10 things in that list.Let's fix that.")

stuff = ten_things.split(' ')#字符串切割函数，并且返回切割后的字符串列表
more_stuff = ["Day","Night","Song","Frisbee","Corn","Banana","Girl","Boy"]#最后入栈最先出栈

while len(stuff) != 10:
     next_one = more_stuff.pop()       #将more_stuff列表中的首个元素出栈，并赋值给next_one变量
     print("Adding:",next_one)         #打印出next_one变量
     stuff.append(next_one)            #追加元素
     print(f"There are {len(stuff)} items now.")

print("There wo go:",stuff)
print("Let's do some things with stuff.")

print(stuff[1])
print(stuff[-1])
print(stuff.pop())#将列表中的第一个元素出栈并且直接打印
print(' '.join(stuff))#
print('#'.join(stuff[3:5]))#

运行截图

*Python split() 通过指定分隔符对字符串进行切片，如果参数 num 有指定值，则分隔 num+1 个子字符串，返回分割后的字符串列表。
*python join()函数详解：，用于将序列中的元素以指定的字符生成一个新的字符串
*stuff[3:5]实现的功能为：这是一个列表的切片动作，它会从列表索引为3的位置开始取值，直至索引为4的元素，注意：这里并不包括索引为5的元素，跟range(3,5)的例子是一样的
*join函数的参数是你要连接的多个字符串构成的数组，是在你要插入的字符串上调用的一个方法函数

习题39：字典
代码展示

stuff = {'name':'zwj','age':22,'weight':106,23:'lky'}
print(stuff['name'])
print(stuff['age'])
print(stuff['weight'])
print(stuff[23])
stuff['city'] = 'beijing'
print(stuff['city'])
stuff[1] = 1998#此时的1不再代表索引位置
print(stuff)

del stuff['name']
print(stuff)

运行截图

*尝试输出print(stuff[1998])，系统提示错误，表示字典中的对应值一般为根据前面的索引后面的

代码展示

#create a mapping of state to abbreviation缩写
states = {
    'Oregon':'OR',
    'Florida':'FL',
    'California':'CA',
    'New York':'NY',
    'Michigan':'MI'
}

#create a basic set of states and some cities in them
cities = {
    'CA':'San Francisco',
    'MI':'Detroit',
    'FL':'Jacksonville'
}

#add some more cities
cities['NY'] = 'New York'
cities['OR'] = 'Portland'

#print out some cities
print('-'*20)
print("NY State has:",cities['NY'])
print("OR State has:",cities['OR'])

#print some states
print('-'*20)
print("Michigan's abbreviation is:",states['Michigan'])
print("Florida's abbreviation is:",states['Florida'])

#print every state abbreviation
print('-'*20)
for state,abbrev in list(states.items()):
    print(f"{state} is abbreviated {abbrev}")

#print every city in state
print('-'*20)
for abbrev,city in list(cities.items()):
    print(f"{abbrev} has the city {city}")

#now do both at the same time
print('-'*20)
for state,abbrev in list(states.items()):
    print(f"{state} is abbreviated {abbrev},and it has city {cities[abbrev]}")

#safely get a abbreviation by state that might be there
print('-'*20)
state = states.get('Taxes')
if not state:
    print("Sorry,no Taxes")
else:
    print("Yes!")

#get a city with a default value
city = cities.get('TX','Does Not Exist')
print(f"The city for the state 'TX' is:{city}")

city = cities.get('MI','Does Not Exist')
print(f"The city for the state 'TX' is:{city}")

运行截图

*Python 字典(Dictionary) items() 函数以列表返回可遍历的(键, 值) 元组数组。
*Python 字典(Dictionary) get() 函数返回指定键的值