文件的读写：
with open(filename, 'a', encoding='utf-8') as file:
with ：后面不必写close文件
第二个参数：‘a’ 追加；‘w’ 写；‘r’ 读
encoding = ‘utf-8’ 编码格式，中文的话一般写上
enter = 'y'
while enter == 'y':name = input("请输入你的名字：")filename = "guest_record.txt"if name != "":with open(filename, 'a', encoding='utf-8') as file:file.write(name + '\n')print("hello, ", name, " !")conti = 'y'while conti == 'y':reason = input("你为什么喜欢python？")with open(filename, 'a', encoding='utf-8') as file:file.write(reason + '\n')conti = input("继续输入原因吗？y/n ")enter = input("继续访问吗？y/n ")
file.readlines() 文件按行读取存在列表内
file.read() 整体读取
filename = 'pi_digits.txt'
with open(filename) as pi_file: #with帮助我们适时关闭文件lines = pi_file.readlines() #把文件按行存储
pi_str = ''
for line in lines:pi_str += line.strip() #strip()行左右的空删除
print(pi_str[:7]+"...")
print(len(pi_str))
birthday = input("输入你的生日：yyyymmdd ")
if birthday in pi_str:print("你的生日出现在pi中。")
else:print("你的生日不在pi中。")
filename = 'learning_python.txt'
with open(filename) as file:'''方法1:整个文件一次读取'''# print(file.read())'''方法2：分行读取'''# for line in file.readlines():# print(line.strip())'''方法3'''line1 = file.readlines()for l in line1:print(l.replace("Python", "C++").strip())
try；except；else（try代码块出错后，执行except部分，未出错，执行else）
错误处理可以使程序不至于崩溃，还可以继续运行
print("input 2 numbers to divide, enter 'q' to quit.")
while True:first = input("\nfirst num: ")if first == 'q':breaksecond = input("\nsecond num: ")try:answer = int(first) / int(second)except ZeroDivisionError:print("divide zero!!!")else:print(answer)breakfilename = 'learning_python.txt'
try:with open(filename) as f_obj:contents = f_obj.read()
except FileNotFoundError:msg = "Sorry, the file " + filename + " does not exist."print(msg)# pass #一言不发，跳过
else:words = contents.split()print("the title ", filename, " has ", str(len(words)), " words.")while True:print("input 2 nums : ")try:a = int(input('first num: '))except ValueError:print("请输入数字！")continuetry:b = int(input('second num: '))except ValueError:print("请输入数字！")continueprint("sum of two nums is ", a+b)
json文件存储
json.dump(object, file)
json.load(file)
import json
numbers = [2, 3, 5, 7, 11, 13]
filename = "numbers.json"
with open(filename,'w') as file:json.dump(numbers,file)with open(filename) as file:numbers = json.load(file)
print(numbers)def get_stored_username():filename = "username.json"try:with open(filename) as file:username = json.load(file)except FileNotFoundError:return Noneelse:return usernamedef get_new_username():username = input("What is your name? ")filename = "username.json"with open(filename, 'a') as file:json.dump(username, file)return usernamedef greet_user():username = get_stored_username()if username:print("Welcome back, ", username, " !")else:get_new_username()print("We'll remember you when you come back, ", username, " !")greet_user()
import json
def get_num():try:global favor_numfavor_num = int(input("输入你喜欢的数字："))except ValueError:print("你输入的不是数字，请重新输入！")get_num()return favor_numdef store_num(num):filename = "user_favor_num.json"with open(filename, 'a') as file:json.dump(num, file)def getAndStore():store_num(get_num())def print_num():filename = "user_favor_num.json"try:with open(filename) as file:num = json.load(file)except FileNotFoundError:getAndStore()else:print("i know your favorite number! it is ", num)print_num()
)
)
