文件和异常练习——python编程从入门到实践

10-1 Python学习笔记：在文本编辑器中新建一个文件，写几句话来总结一下你至此学习到的python知识，其中每一行都以“In Python you can”打头。将这和文件命名为learning_python.txt，并将其存储到为完成本章节练习而编写的程序所在的目录。编写一个程序，它读取这个文件，并将所写内容打印三遍：第一次打印时读取整个文件；第二次打印时遍历文件对象；第三次打印时将各行内容存储到一个列表中，再在with代码块外打印它们。

with open('learning_python.txt') as file_object:
    contents = file_object.read()
    print(contents.rstrip())

with open('learning_python.txt') as file_object:
    for line in file_object:
        print(line.rstrip())

with open('learning_python.txt') as file_object:
    lines = file_object.readlines()

string = ''
for line in lines:
    string = string + line.strip()

print(string)

10-2 C语言学习笔记：可使用方法replace()将字符串中的特定单词都替换为另一个单词。下面是一个简单的示例，演示了如何将句子中的“dog”替换为“cat”:

message = "I really like doges."
print(message.replace('dog', 'cat'))

　　读取刚创建的文件learning_python.txt中的每一行，将其中Python都替换为另一门语言，如C。将修改后的各行都打印到屏幕上。

with open('learning_python.txt') as file_object:
    for line in file_object:
        line = line.replace('Python', 'C')
        print(line.rstrip())

10-3 访客：编写一个程序，提示用户输入其名字；用户做出响应后，将其名字写入到文件guest.txt中。

filename = 'guest.txt'
with open(filename, 'w') as file_object:
    name = input('Please enter your name: ')
    file_object.write(name)

10-4 访客名单：编写一个while循环，提示用户输入其名字。用户输入其名字后，在屏幕上打印一句问候语，并将一条访问记录添加到文件guest.txt中。确保这个文件中的每条记录都独占一行。

filename = 'guest.txt'
with open(filename, 'w') as file_object:
    while True:
        name = input("Please enter your name and enter 'q' to quit: ")
        if name == 'q':
            break
        else:
            great_user = "Hello " + name + ".\n"
            print(great_user)
            file_object.write(great_user)

10-5 关于编程的用户调查：编写一个while循环，询问用户为何喜欢编写。每当用户输入一个原因后，都将添加到一个存储所有原因的文件中。

filename = 'The reason of like programming.txt'
with open(filename, 'w') as file_object:
    file_object.write("The reason of our like programming:\n")
with open(filename, 'a') as file_object:
    while True:
        reason = input("Enter the reason of you like programming and if enter 'q' to quit: ")
        if reason == 'q':
            break
        else:
            file_object.write(reason + '\n')