笨办法学Python（learn python the hard way）--练习程序11-20

#ex11.py
1 print("How old are you?",end=''),
age = input()
print("How tall are you?",end=''),
height = input()
print("How much do you weigh?",end=''),
weight = input()

print(f"So,you're {age} old,{height} tall and {weight} heavy.")

#ex12.py
1 age = input("How old are you?")
height = input("How tall are you?")
weight = input("How much do you weigh?")

print(f"So,you're {age} old,{height} tall and {weight} heavy.")

#ex13.py
1 from sys import argv

script, first, second, third = argv
a=input("what's your name?")
print(a)
print("The script is called:", script)
print("Your first variable is:", first)
print("Your second variable is:", second)
print("Your third variable is:", third)

 #ex14.py
 1 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 questions.")
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))

 #ex15.py
 1 from sys import argv

script, filename = argv

txt = open(filename)

print("Here's your file %r:"%filename)
print(txt.read())
txt.close()

print("Type the filename again:")
file_again = input("> ")

txt_again = open(file_again)

print(txt_again.read())
txt_again.close()

附ex15_sample：This is stuff I typed into a file.
It is really cool stuff.
Lots and lots of fun to have in here.

 #ex16.py
 1 from sys import argv

script, filename = argv

print("We're going to erase %r."%filename)
print("If you don't want that, hit CTRL-C(^C).")
print("If you do want that, hit RETURN.")

#input作用是中断程序，选择是否要删除文件内容
input("?")

print("Opening the file...")
#'w'是open的参数，默认是读，只有特别指定才可以进入写操作，写操作是先删除再新建，所以后面的truncate实际是不起作用的
target = open(filename, 'w')

print("Truncating the file. Goodbye!")
target.truncate()

print("Now I'm going to ask you for three lines.")

line1 = input("line 1: ")
line2 = input("line 2: ")
line3 = input("line 3: ")

print("I'm going to write these to the file.")

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
 1 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 line too, how?
#indata = open(from_file).read()
input = open(from_file)
indata = input.read()

print("The input file is %d bytes long"%len(indata))

print("Does the output file exist?%r" %exists(to_file))
print("Ready, hit RETURN to continue, CTRL-C to abort.")
input("??")

output = open(to_file, 'w')
output.write(indata)
print("Alright,all done.")

output.close()
input.close()

 #ex18.py
 1 # this one is like your scripts with argv
def print_two(*args):
 arg1, arg2 = args
 print("arg1: %r, arg2: %r"%(arg1, arg2))
    
# ok, that *args is actually pointless, we can just do this
def print_two_again(arg1, arg2):
 print("arg1: %r, arg2: %r"%(arg1, arg2))
 
# this just takes one argument
def print_one(arg1):
 print("arg1: %r"% arg1)
 
# this one takes no arguments
def print_none():
 print("I got nothin'.")
 

print_two("Zed","Shaw")
print_two_again("Zed","Shaw")
print_one("Frist!")
print_none()

 #ex19.py
 1 # 函数里边的变量和脚本里边的变量之间是没有连接的
def cheese_and_crackers(cheese_count, boxes_of_crackers):
    print("You have %d cheeses!"%cheese_count)
    print("You have %d boxes of crackers!"%boxes_of_crackers)
    print("Man that's enough for a party!")
    print("Get a blanket.\n")
    
    
print("We can just give the function numbers directly:")
cheese_and_crackers(20,30)


print("OR, we can use variables from our script:")
amount_of_cheese = 10
amount_of_crackers = 50

cheese_and_crackers(amount_of_cheese, amount_of_crackers)


print("We can even do math inside too:")
cheese_and_crackers(10+20,5+6)


print("And we can combine the two, variables and math:")
cheese_and_crackers(amount_of_cheese + 100, amount_of_crackers + 1000)

 #ex20.py
 1 #函数和文件如何一起协作
from sys import argv
script, input_file = argv

#定义函数：将读到的内容打印出来
def print_all(f):
    print(f.read())

#定义函数：将光标定位到起始位置    
def rewind(f):
    f.seek(0)

#定义函数： 将读到的行数及该行内容打印出来   
def print_a_line(line_count, f):
    print(line_count, f.readline())

#打开文件    
current_file = open(input_file)

print("First let's print the whole file:\n")

print_all(current_file)

print("Now let's rewind, kind of like a tape.")

rewind(current_file)

print("Let's print three lines:")

#current_line = 0
#current_line += 1
current_line = 1
print_a_line(current_line, current_file)

current_line = current_line + 1
print_a_line(current_line, current_file)

current_line = current_line + 1
print_a_line(current_line, current_file)