96 lines
2.6 KiB
Markdown
96 lines
2.6 KiB
Markdown
# Python 中的文件处理备忘单
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> 原文：<https://www.pythonforbeginners.com/cheatsheet/python-file-handling>
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## 文件处理
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Python 中的文件处理不需要导入模块。
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## 文件对象
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相反，我们可以使用内置对象“文件”。默认情况下，该对象提供了操作文件所需的基本函数和方法。在读取、追加或写入文件之前，首先必须使用 Python 的内置 open()函数。在这篇文章中，我将描述如何使用文件对象的不同方法。
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## 打开()
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open()函数用于打开我们系统中的文件，filename 是要打开的文件的名称。模式指示文件将如何打开:“r”表示读取,“w”表示写入,“a”表示追加。open 函数有两个参数，文件名和打开文件的模式。默认情况下，当只传递文件名时，open 函数以读取模式打开文件。
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## 例子
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这个小脚本将打开(hello.txt)并打印内容。这将把文件信息存储在文件对象“文件名”中。
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```py
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filename = "hello.txt"
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file = open(filename, "r")
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for line in file:
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print line,
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```
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## 阅读()
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read 函数包含不同的方法，read()、readline()和 readlines()
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```py
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read() #return one big string
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readline #return one line at a time
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read-lines #returns a list of lines
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```
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## 写()
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此方法将一系列字符串写入文件。
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```py
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write () #Used to write a fixed sequence of characters to a file
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writelines() #writelines can write a list of strings.
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```
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## 追加()
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append 函数用于追加到文件中，而不是覆盖它。要追加到现有文件，只需在追加模式(“a”)下打开文件:
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## 关闭()
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当您处理完一个文件时，使用 close()关闭它并释放被打开的文件占用的所有系统资源
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## 文件处理示例
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让我们展示一些例子
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```py
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To open a text file, use:
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fh = open("hello.txt", "r")
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To read a text file, use:
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fh = open("hello.txt","r")
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print fh.read()
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To read one line at a time, use:
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fh = open("hello".txt", "r")
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print fh.readline()
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To read a list of lines use:
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fh = open("hello.txt.", "r")
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print fh.readlines()
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To [write to a file](https://www.pythonforbeginners.com/files/reading-and-writing-files-in-python), use:
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fh = open("hello.txt","w")
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write("Hello World")
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fh.close()
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To [write to a file](https://www.pythonforbeginners.com/files/reading-and-writing-files-in-python), use:
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fh = open("hello.txt", "w")
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lines_of_text = ["a line of text", "another line of text", "a third line"]
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fh.writelines(lines_of_text)
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fh.close()
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To append to file, use:
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fh = open("Hello.txt", "a")
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write("Hello World again")
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fh.close()
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To close a file, use
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fh = open("hello.txt", "r")
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print fh.read()
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fh.close()
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``` |