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中的內置方法，用于創建，打開或附加文件。

Syntax:

句法：

    file_object = open(file_name, file_mode)

Parameter(s):

參數：

• 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 –這是一個可選參數，用于指定各種文件模式。

  • w – Opens the file in write mode i.e. creates a file.
  • w –以寫模式打開文件，即創建文件。
  • r – Opens the file in reading mode.
  • r –以讀取模式打開文件。
  • a – Opens the file in append mode.
  • a –以追加模式打開文件。
  • x – Creates the file, if file exists it returns an error.
  • x –創建文件，如果文件存在則返回錯誤。
  • 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進制模式(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.

該方法的返回類型為<class'_io.TextIOWrapper'> ，它返回一個文件對象。

Example 1:

范例1：

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

Output

輸出量

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 file
f = open("hello.txt", "w")
print("file created...")
print(f) # prints file details
# opening created file in read mode
f = 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

輸出量

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 exist
f = open("myfile.txt") # returns an error

Output

輸出量

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

翻譯自: https://www.includehelp.com/python/file-open-method-with-example.aspx

python 示例