[C]增加了第10章 文件和异常的相关操作

Signed-off-by: VincentJ <im.vincentj@gmail.com>

Author: VincentJ1989

chapter9/alice.py

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+# 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)
+
+# 分析文本
+title = "Alice in Wonderland"
+print(title.split())

chapter9/alice.txt

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+In the first half of the book, you’ll learn about basic programming concepts, such as lists, dictionaries, classes, and loops, and practice writing clean and readable code with exercises for each topic. You’ll also learn how to make your programs interactive and how to test your code safely before adding it to a project. In the second half of the book, you’ll put your new knowledge into practice with three substantial projects: a Space Invaders–inspired arcade game, data visualizations with Python’s super-handy libraries, and a simple web app you can deploy online.

chapter9/exception.py

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+# 异常处理
+
+try:
+    print(5 / 0)
+except ZeroDivisionError:
+    print("You can't divide by zero!")
+
+# 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:
+        pass
+        print("You can't divide by 0!")
+    else:
+        print(answer)

chapter9/file_reader.py

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+# 读文件
+with open('pi_digits.txt') as file_object:
+    contents = file_object.read()
+    # print(contents)
+    # print(contents.rstrip())
+    
+    # 分行打印--这里可以看到空行
+    # for line in file_object:
+    #     print(line)
+    # 去空行
+    # print(line.rstrip())
+    
+    # 一次读出所有行
+    # lines = file_object.readlines()
+    # for line in lines:
+    #     print(line.rstrip())
+
+# 其他位置
+with open('../pi.txt') as file_obj:
+    contents2 = file_obj.read()
+    print(">>>" + contents2)
+    # 去除开头的空格
+    print('>>>' + contents2.strip())
+    
+    print('1415' in contents2)

chapter9/number_reader.py

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+# 读json
+import json
+
+file_name = "number.txt"
+with open(file_name) as file_object:
+    numbers = json.load(file_object)
+    print(numbers)

chapter9/number_writer.py

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+# 存储数据--写json
+
+import json
+
+numbers = [2, 3, 5, 7, 11, 13]
+file_name = "number.txt"
+with open(file_name, 'w') as file_object:
+    json.dump(numbers, file_object)

chapter9/pi_digits.txt

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+3.1415926535
+8979323846
+ 2643383279

chapter9/word_count.py

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+def count_words(filename):
+    """计算一个文件大致包含多少个单词"""
+    try:
+        with open(filename) as f_obj:
+            contents = f_obj.read()
+    except FileNotFoundError:
+        # 当然也可以使用pass忽略该异常提醒
+        # pass
+        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.")
+
+
+filename = 'alice.txt'
+count_words(filename)

chapter9/write_message.py

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+# 写入文件
+file_name = 'programming.txt'
+# 默认不传'w'是指只打开文件'r'
+# 读取模式（'r'）、写入模式('w'）、附加模式（'a'）或让你能够读取和写入文件的模式（'r+'）
+with open(file_name, 'w') as file_object:
+    # 写单行
+    file_object.write("I like Python.")
+    # 在写一行-- 发现挤在一起了
+    file_object.write("I like Kotlin.\n")
+    # 加换行符即可
+    file_object.write("I like Julia.\n")
+
+# 额外添加信息到文本末尾
+with open(file_name, 'a') as file_object:
+    file_object.write("I also love finding meaning in large datasets.\n")
+    file_object.write("I love creating apps that can run in a browser.\n")

pi.txt

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+   3.1415926535 8979323846 2643383279