python 示例

文件open()方法 (File open() Method)

open() method is an inbuilt method in Python, it is used to create, open or append a file.

open()方法是Python中的内置方法，用于创建，打开或附加文件。

Syntax:

句法：

file_object = open(file_name, file_mode)

Parameter(s):

参数：

• file_name – It is used to specify the file name.

  file_name –用于指定文件名。

• file_mode – It is an optional parameter, it is used to specify the various file modes.

  file_mode –这是一个可选参数，用于指定各种文件模式。

  • w – Opens the file in write mode i.e. creates a file.
  • w –以写模式打开文件，即创建文件。
  • r – Opens the file in reading mode.
  • r –以读取模式打开文件。
  • a – Opens the file in append mode.
  • a –以追加模式打开文件。
  • x – Creates the file, if file exists it returns an error.
  • x –创建文件，如果文件存在则返回错误。
  • t – It is used to file modes to specify the text mode (Example: wt, rt, at, and xt).
  • t –用于文件模式以指定文本模式(例如： wt ， rt ， at和xt )。
  • b – It is used to file modes to specify the binary mode (Example: wb, rb, ab, and xb).
  • b –用于文件模式以指定二进制模式(例如： wb ， rb ， ab和xb )。

Return value:

返回值：

The return type of this method is <class '_io.TextIOWrapper'>, it returns a file object.

该方法的返回类型为<class'_io.TextIOWrapper'> ，它返回一个文件对象。

Example 1:

范例1：

# Python File open() Method with Exampleprint("creating files...")# creating a file without specifying mode (b or t)file1 = open("hello_1.txt", "w")# creating a file in binary modefile2 = open("hello_2.txt", "wb")# creating a file in text modefile3 = open("hello_3.txt", "wt")print("file creation operation done...")# printing the details of file objectsprint(file1)print(file2)print(file3)

Output

输出量

creating files...file creation operation done...<_io.TextIOWrapper name='hello_1.txt' mode='w' encoding='UTF-8'><_io.BufferedWriter name='hello_2.txt'><_io.TextIOWrapper name='hello_3.txt' mode='wt' encoding='UTF-8'>

Example 2:

范例2：

# Python File open() Method with Example# creating a filef = open("hello.txt", "w")print("file created...")print(f) # prints file details# opening created file in read modef = open("hello.txt", "r")print("file opened...")print(f) # prints file details# opening file in append mode f = open("hello.txt", "a")print("file opened in append mode...")print(f) # prints file details

Output

输出量

file created...<_io.TextIOWrapper name='hello.txt' mode='w' encoding='UTF-8'>file opened...<_io.TextIOWrapper name='hello.txt' mode='r' encoding='UTF-8'>file opened in append mode...<_io.TextIOWrapper name='hello.txt' mode='a' encoding='UTF-8'>

Example 3:

范例3：

# Python File open() Method with Example# opening a file that doesn't existf = open("myfile.txt") # returns an error

Output

输出量

Traceback (most recent call last):  File "main.py", line 4, in 
    
        f = open("myfile.txt") # returns an errorFileNotFoundError: [Errno 2] No such file or directory: 'myfile.txt'
    

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python 示例