python练习题-20170916
周末开始第一次尝试对着书写代码练习题
《笨办法学python》--作者Zed A.Shaw，翻译Wang Dingwei
ex1.py
print('hello world')
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ex2.py
#A comment, this is so you can read your program later.
#Anything after the # is ignored by python.
print('i could have code like this') # and the comment after is ignored.
#you can also use a comment to 'disable' or comment out pieve of code.
#print "this won't run"
print('this will run')
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ex3.py
print('i will now count my chickens')
print('hens',25+30/6)
print('rooster',100-25*3%4)
print('now i will count my eggs:')
print(3+2+1-5+4%2-1/4+6)
print('is it ture that 3+2<5-7?')
print(3+2<5-7)
print('what is 3+2?',3+2)
print('what is 5-7?',5-7)
print("oh that's why it's False.")
print('how about some more?')
print('is it greater?',5>2)
print('is it great or equal?',5>=2)
print('is it less or equal?',5<=2)
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ex4.py
cars=100
space_in_a_car=4.0
drivers=30
passangers=90
cars_not_driven=cars-drivers
cars_driven=drivers
carpool_capacity=cars_driven*space_in_a_car
average_passagers_per_car=passangers / cars_driven
#变量之间要用,隔开，不能用空格
print('there are',cars,'cars available.')
print('there are only',drivers,'drivers avalilable.')
print('there will be',cars_not_driven,'emtpy cars today.')
print('we can transport',carpool_capacity,'people today.')
print('we have',passangers,'to carpool today.')
print('we need to put about',average_passagers_per_car,'in each car.')
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ex5.py
my_name = 'zed a. shaw'
my_age = 35 #not a lie
my_height = 74 #inches
my_weight = 180 #lbs
my_eyes = 'blue'
my_teeth = 'white'
my_hair = 'brown'
#%str表示格式化字符串
print("let's talk about %s." %my_name)
print("he's %d inches tall." %my_height)
print("he's %d pounds heavy." %my_weight)
print("actually it is not too heavy.")
print("he's got %s eyes and %s hair." %(my_eyes,my_hair))
print("his teeth are usually %s depending on the coffee." %my_teeth)
#this line is tricky,try to get it exactly right.
print('if i add %d,%d and %d i get %d.' %(my_age,my_height,my_weight,my_age+my_height+my_weight))
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ex6.py
#%d表示转化成10进制整数
x = "there are %d types pf people." % 10
binary = "binary"
do_not = "don't"
#%s表示转化成字符串
y = "those who knows %s and those who %s." %(binary,do_not)
print(x)
print(y)
#%r表示？
print("i said: %r." %x)
print("i also said: '%s'." %y)
hilarious = False
joke_evaluation = "isn't that joke so funny?! %r"
print(joke_evaluation % hilarious)
w = "this is the left side of ..."
e = "a string with a right side."
print(w+e)
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ex7.py
print("mary had a little lamb")
print("its fleece was white as %s." %'snow')
print("and everywhere that mary went")
print("."*10) #what's that do?
end1 ="c"
end2 ="h"
end3 ="e"
end4 ="e"
end5 ="s"
end6 ="e"
end7 ="B"
end8 ="u"
end9 ="r"
end10 ="g"
end11 ="e"
end12 ="r"
#watch that comma at the end. try removing it to what happens
print(end1 + end2 + end3 + end4 + end5 + end6)
print(end7 + end8 + end9 + end10 + end11 + end12)
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ex8.py
formatter = "%r %r %r %r"
print (formatter % (1,2,3,4))
print (formatter % ("one","two","three","four"))
print (formatter % (True,False,False,True))
print (formatter % (formatter,formatter,formatter,formatter))
print (formatter % (
"i had this thing.",
"that you could type up right.",
"but it didn't sing.",
"so i said goodnight")
)
#print后面要紧跟(),括号内不同字符串之间要,隔开
#括号内字符串要用"",其他数据类型不用""
#formatter是个变量，表示字符串
------------------------------------------------------------------
ex9.py
#here's some new strange stuff,remeber type it excatly.
days = "mon tue wed thu fri sat sun"
mouths = "jan\nfeb\nmar\napr\nmay\njun\njul\naug"
print("here are the days:",days)
print("here are the mouths:",mouths)
("""
there's something going on here.
with the three double-quotes.
we'll be able to type as much as we like.
even 4 lines if we want,or 5,or 6.
""")
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ex10.py
tabby_cat = "\t i'm tabbed in."
persian_cat = "i'm split\non a line."
backslash_cat = "i'm \\ a \\ cat."
fat_cat = """
i'll do a list:
\t* cat food
\t* fishies
\t* catnip \n \t* grass
"""
print(tabby_cat)
print(persian_cat)
print(backslash_cat)
#\t转义为tab
#\n转义为下一行
#\\转义为\
#\r转义为回车
#\f转义为换页
------------------------------------------
ex11.py
print("how old are you?"),
age = input()
print("how tall are you?"),
height = input()
print("how much do you weigh?"),
weigh = input()
print("so, you're %r old, %r tall and %r heavy." %(age,height,weigh))
#python3里input代替raw_input
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ex12.py
y = input("name?")
age = input("how old are you?")
height =input("how tall are you?")
weigh =input("how much do you weigh?")
print("so,you're %r old,%r tall and %r heavy." %(age,height,weigh))
#python -m pydoc open/file/os/sys/input
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ex13.py
from sys import argv
script, first, second, third = argv
print("the script is called:",script)
print("your first variable is:",first)
print("your second variable is:",second)
print("your third variable is:",third)
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ex14.py
from sys import argv
script,user_name = argv
prompt = '>'
print("hi %s,i'm the %s script." %(user_name,script))
print("i'd like to ask you a few question.")
print("do you like me %s" %(user_name))
likes = input(prompt)
print("where do you live? %s" %(user_name))
lives = input(prompt)
print("what kind of computer do you have?")
computer = input(prompt)
print ("""alright, so you said %r about liking me.
you live in %r.not sure where that is.
and you have a %r computer.nice."""%(likes,lives,computer))
#python3中，print的内容必须全部在（）内
#sys=system
#sys.argv是一个字符串列表，也是一个命令行参数列表（使用命令行传递给程序参数的列表）
#从命令行输入python 程序名称.py 内容，内容被作为参数传递给程序，储存在sys.argv中
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ex15.py
from sys import argv
script,filename = argv
txt = open(filename)
print("here's your file %r:" %filename)
print(txt.read())
#read是open命令的一个函数
print("type the filename again:")
file_again = input(">") #将输入的内容赋值给file_again
txt_again = open(file_again) #使用open函数打开输入的文件，赋值给txt_again
print(txt_again.read()) #输出读取到文件的内容
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ex16.py
from sys import argv
script,filename = argv
print("we're going to erase %r." %filename)
print("if you don't want do that,hit ctrl-c(^c)")
print("if you do want that,hit return")
input("?")
#对文件使用open命令，要赋值给一个变量，通过变量进行参数操作，操作方法就是变量名.参数
print("open the file...")
target = open(filename,"w")
#open命令里面的w参数是指文件若存在，首先要清空，然后（重新）创建
print("truncating the file,goodbye")
target.truncate() #truncate是清空文件内全部内容
print("now i'm going to ask you for three lines")
line1 = input("line 1:") #向文件内输入内容
line2 = input("line 2:")
line3 = input("line 3:")
print("i'm going to write there to the file")
line = str(line1+'\n'+line2+'\n'+line3)
#尝试新方法：新建一个变量line，将输入的line1、line2与line3赋值给line，中间写入'\n'换行符
target.write(line)
#write后面的参数指输入的内容变量
# target.write(line1)
# target.write("\n")
# target.write(line2)
# target.write("\n")
# target.write(line3)
# target.write("\n")
print("and finally,we close it")
target.close()
------------------------------------------------------------------------------------
ex17.py
from sys import argv
from os.path import exists
script,from_file,to_file = argv
print("copying from %s to %s" %(from_file,to_file))
#we could do these two on one lines too,how?
input1 = open(from_file) #打开from_file赋值给input变量
indata = input1.read() #读取from_file的内容赋值给indata，就是需要copy的内容
print("the input file is %d bytes long" %len(indata)) #输出copy的长度
print("does the output file exist? %r" %exists(to_file)) #输出目标文件是否存在
print("ready,hit return to continue,ctrl-c to abort.")
input = ()
#输入内容
output =open(to_file,'w') #新建to_file文件赋值给output变量
output.write(indata) #将需要copy的内容写入to_file文件
print("alright,all done")
output.close()
input1.close()
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ex18.py
#命名、变量、代码、函数
#this one is likes your scripts with argv
#*argument表示动态变量，可以不受数量限制
def print_two(*args):
arg1,arg2 = args
print("arg1:%r,arg2:%r" %(arg1,arg2))
#ok,this *args is actuallu pointless,we can just do this.
def print_two_again(arg1,arg2):
print("arg1:%r,arg2:%r" %(arg1,arg2))
#this just take one argument.
def print_one(arg1):
print("arg1:%r" %arg1)
#this one take none argument.
def print_none():
print("i got nothing")
print_two("zed","shaw")
print_two_again("zed","shaw")
print_one("first")
print_none()
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ex19.py
#函数和变量
def cheese_and_crackers(cheese_count,box_of_crackers):
print("you have %d cheeses" %cheese_count)
print("you have %d crackers" %box_of_crackers)
print("man that is enough for party.")
print("get a blanket. \n")
print("we can just give the function numbers dirctly.")
cheese_and_crackers(20,30)
print("oh,we can use variables from the script:")
amount_of_cheese = 10
amount_of_crackers = 50
cheese_and_crackers(amount_of_cheese,amount_of_crackers)
print("we can even do math insides too:")
cheese_and_crackers(10+20,5+6)
print("we can also combine the two,variables and math:")
cheese_and_crackers(amount_of_cheese+100,amount_of_crackers+1000)
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ex20.py
#习题20：函数和文件
from sys import argv
script,input_file = argv #intut_file为待输入的文件
def print_all(f): #定义第一个函数为print_file，作用为读取文件
print(f.read())
def rewind(f): #定义第二个函数为rewind，作用为查找文件里面的内容
f.seek(0)
def print_a_line(line_count,f):
print(line_count,f.readline())
#定义第三个函数为print_a_line，作用为输出某一行的内容，第一个参数为指定的某行，第二个参数为读取该行内容
current_file = open(input_file) #将打开输入的文件赋值给变量current_file——当前文件
print("first,let's print the whole file:\n")
print_all(current_file) #执行函数print_all，目标是当前文件
print("let's rewind,kind of like a tape.")
rewind(current_file) #执行函数rewind，目标是当前文件
print("let's print three lines.")
current_line = 1 #将1赋值给变量current_line——当前行
print_a_line(current_line,current_file) #执行函数print_a_line，对当前文件的第一行
current_line = current_line + 1 #current_line自增1，等于2
print_a_line(current_line,current_file) #执行函数print_a_line，对当前文件的第二行
current_line = current_line + 1 #current_line自增1，等于3
print_a_line(current_line,current_file) #执行函数print_a_line，对当前文件的第三行
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ex21.py
#习题21：函数可以返回东西
def add(a,b):
print("adding %d + %d"% (a,b))
return(a + b) #return是用来将函数运行的结果返回
def subtract(a,b):
print("subtracting %d - %d"%(a,b))
return(a - b)
def mutiply(a,b):
print("mutipling %d * %d"%(a,b))
return(a * b)
def devide(a,b):
print("deviding %d / %d"%(a,b))
return(a / b)
#print内，格式化字符的%前面不能有,
print("let's do some math with just functions.")
age = add(30,5)
heigh =subtract(78,4)
weight =mutiply(90,2)
iq = devide(100,2)
#a puzzle for the extra credit,type it in anyway.
print("here is a puzzle.")
what =add(age,subtract(heigh,mutiply(weight,devide(iq,2))))
print("that becomes ",what,"can you do it by hand?")
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2017-09-17 22:56:03
