#coding=gbk#Python编程从入门到实践笔记——异常和存储数据#10.3异常#Python使用被称为异常的特殊对象来管理程序执行期间发生的错误。每当发生让Python不知所措的错误时，它都会创建一个异常对象。#如果编写了处理该异常的代码，程序将继续运行；如果你未对异常进行处理，程序将停止，并显示一个traceback，其中包含有关异常的报告。#异常是使用try-except代码块处理的。try-except 代码块让Python执行指定的操作，同时告诉Python发生异常时怎么办。#使用了try-except代码块时，即便出现异常，程序也将继续运行：显示你编写的友好的错误消息，而不是令用户迷惑的traceback。 #1.处理ZeroDivisionError异常#print(5/0) #2.使用try-except 代码块try:    print(5/0)except ZeroDivisionError:    print("You can't devide by zero.")  #3.使用异常避免崩溃 #4.else 代码块#依赖于try 代码块成功执行的代码都应放到else 代码块中：print("Give me two numbers, and I'll divide them.")print("Enter 'q' to quit.")while True:    first_number = input("\nFirst number: ")    if first_number == 'q':        break    second_number = input("Second number: ")    try:        answer = int(first_number) / int(second_number)    except ZeroDivisionError:        print("You can't divide by 0!")    else:        print(answer) #5.处理FileNotFoundError异常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) #6.分析文本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)else:    # 计算文件大致包含多少个单词    words = contents.split()    num_words = len(words)    print("The file " + filename + " has about " + str(num_words) + " words.") #7.使用多个文件def count_words(filename):    """--snip--"""    filenames = ['alice.txt', 'siddhartha.txt', 'moby_dick.txt', 'little_women.txt']for filename in filenames:    count_words(filename) #8.失败时一声不吭 pass语句def count_words(filename):    """计算一个文件大致包含多少个单词"""    try:        """--snip--"""    except FileNotFoundError:        pass    else:        """--snip--"""  #10.4存储数据#1.使用json.dump() 和json.load()import json numbers = [2, 3, 5, 7, 11, 13]filename = 'numbers.json'with open(filename, 'w') as f_obj:    json.dump(numbers, f_obj)  #2.保存和读取用户生成的数据import json username = input("What is your name? ")filename = 'username.json'with open(filename, 'w') as f_obj:    json.dump(username, f_obj)    print("We'll remember you when you come back, " + username + "!") with open(filename) as f_obj:    username = json.load(f_obj)    print("Welcome back, " + username + "!")