python3基础8-文件和异常

#coding:utf-8
#write file 覆盖之前的文件
#with open("1.txt","w") as b:
#  b.write("today is a good day")
#write file 在之前的文件后面新加
#with open("1.txt","a") as b:
#  b.write("\ntoday is a ok day")
#读取和写入模式打开,覆盖之前的内容并且第一行留空
with open("1.txt","r+") as b:
    b.write("\ntoday is a r day")

#read file
#默认为只读r
with open("1.txt") as a:
    '''
    c = a.read()
    print(c.rstrip())
    '''
    '''
    for line in a:
        print(line.rstrip())
    '''
    lines = a.readlines()
    for line in lines:
        print(line.rstrip())

#json数据存储
import json
numbers = [2, 3, 5, 7, 11, 13]
filename = 'numbers.json'
with open(filename,'w') as f_obj:
    json.dump(numbers, f_obj)

with open(filename) as f_obj:
    numbers = json.load(f_obj)
    print(numbers)

#异常
try:
    print(5/0)
except ZeroDivisionError:
    print("zero")

try:
    print(5/0)
except ZeroDivisionError:
#什么也不做
    pass

try:
    print(5/2)
except ZeroDivisionError:
    print("zero")
else:
    print("ok")

filename = 'alice.txt'
try:
    with open(filename) as f_obj:
        contents = f_obj.read()
except FileNotFoundError:
    msg = "Sorry, the file " + filename + " does not exist."
    print(msg)