《Python 编程：从入门到实践》第十章(文件和异常)练习题答案

# -*- coding: utf-8 -*-
#with open('xlh.txt') as file_object:
	#contents = file_object.read()
	#print(contents)
	#存储到列表中
	#lines = file_object.readlines()
	#for line in file_object:
	#	print(line.rstrip())


with open('xlh2.txt') as file_object:
	result_string = ''
	for line in file_object:
		result_string+=line.strip()
	print(result_string.replace('f','kkk'))
#10-3

quit_flag = False
while quit_flag==False:
	username = input('please input your name:')
	if username!='q':
		with open('guest_book.txt','a') as file_object:
			file_object.write(username+'\n')
	else:
		quit_flag = True
	
	
		
try:
	print(5/0)
except  ZeroDivisionError:
	print("you can't divide by zero")
	
	
	
#10-7:加法运算
while True:
	first_num = input('请输入第一个值：')
	if first_num == 'q':
		break
	second_num = input('请输入第二个值：')
	if second_num =='q':
		break
	try:
		result = int(first_num) + int(second_num)
	except ValueError:
		print('请核实两个都是数字')
	else:
		print(result)
#10-8,9
file_list = ['dogs.txt','dog.txt','cats.txt']
for file_name in file_list:
	try:
		with open(file_name) as file_object:
			contents = file_object.read()
	except FileNotFoundError:
		pass
		#print('file',file_name,'not found!')
	else:
		print(contents)
#10-10
with open('xlh.txt') as file_object:
	contents = file_object.read()
	num_words = contents.split()
	print(len(num_words))
	print(contents.upper().count('A'))
	
	
import json
numbers = [2,3,4,5,6]
filename = 'numbers.json'
with open(filename,'w') as file_object:
	json.dump(numbers,file_object)
	
import json
filename = 'numbers.json'
with open(filename) as file_object:
	numbers = json.load(file_object)
print(numbers)

import json
filename = 'userinfo.json'
def get_stored_user():
	try:
		with open(filename) as file_object:
			username = file_object.read()
			#username = json.load(file_object)
	except FileNotFoundError:
		return None
	else:
		return username
def greet_user():
	username = get_stored_user();
	if username:
		print('Hello,',username,'welcome back')
	else:
		with open(filename,'w') as file_object:
			username = input('please input your name:')
			file_object.write(username)
			#json.dump(username,file_object)
			print('we rembered you ',username)		
		
greet_user()
	
#10-11
import json
filename = 'favnum.json'
def get_stored_user():
	try:
		with open(filename) as file_object:
			favnum = json.load(file_object)
	except FileNotFoundError:
		return None
	else:
		return favnum
def show_favoritenum():
	favnum = get_stored_user();
	if favnum:
		print('your favorite num is',favnum)
	else:
		with open(filename,'w') as file_object:
			favnum = input('please input your favorite num:')
			json.dump(favnum,file_object)
			print('we rembered your favorite num ',favnum)		
		
show_favoritenum()

#10-13
import json
filename = 'userinfo.json'
def get_stored_user():
	try:
		with open(filename) as file_object:
			username = json.load(file_object)
	except FileNotFoundError:
		return None
	else:
		return username
def store_user():
	with open(filename,'w') as file_object:
		username = input('please input your name:')
		json.dump(username,file_object)
		print('we rembered you ',username)
def greet_user():
	username = get_stored_user();
	if username:
		print('Hello,',username,'welcome back')
		confirmInfo = input('is this your count,Y or N?:')
		if confirmInfo == 'N':
			store_user()
	else:
		store_user()		
		
greet_user()