Python open() Method
The open() method opens the file (if possible) and returns the corresponding file object.
open() Syntax:
open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, opener=None)Parameters:
- file: The path name of the file to be opened or an integer file descriptor of the file to be wrapped.
- mode: (Optional) An access mode while opening a file. Default mode is ‘r’ for reading. See all the access modes.
- buffering: (Optional) Used for setting buffering policy. Defaults to -1. Pass 0 if specified mode is binary ‘b’,
- encoding: (Optional) The encoding format to encode or decode the file.
- errors: (Optional) String specifying how to handle encoding/decoding errors.
- newline: (Optional) Conrols how newlines mode works. It can be None, », ‘\n’, ‘\r’, and ‘\r\n’.
- Closefd: (Optional) If a filename is given, it must be True. If False, the file descriptor will be kept open when the file is close
- Opener: (Optional) A custom callable file opener.
Return type:
File Access Modes
The following table lists the file access modes parameter values.
| Access Modes | Description |
|---|---|
| r | Opens a file for reading only. |
| rb | Opens a file for reading only in binary format. |
| r+ | Opens a file for both reading and writing. |
| rb+ | Opens a file for both reading and writing in binary format. |
| w | Opens a file for writing only. |
| wb | Opens a file for writing only in binary format. |
| w+ | Opens a file for both writing and reading. |
| wb+ | Opens a file for both writing and reading in binary format. |
| a | Opens a file for appending. |
| ab | Opens a file for appending in binary format. |
| a+ | Opens a file for both appending and reading. |
| ab+ | Opens a file for both appending and reading in binary format. |
The following example opens a file from the current directory for reading and writing to file. The current directory in Python shell is C:\python38 .
>>> f = open("MyFile.txt") # Open MyFile.txt from the current directory for reading >>> f = open("MyFile.txt", 'w') # Open MyFile.txt from the current directory for writing # perform file operations using f >>> f.close() The file operations can raise exceptions if something goes wrong. So, it is recommended to use try-except-finally to handle exceptions and closing a file object.
try: f = open("MyFile.txt") # Open MyFile.txt from the current directory for reading # perform file operations using f except: # handle exceptions finally: f.close() The following example opens files for read, write or update operations.
>>> f = open("C:\MyFile.txt") # open for reading >>> f = open("C:\MyFile.txt",'w') # open for writing >>> f = open("C:\MyFile.txt", 'x') # open for exclusive creation >>> f = open("C:\MyFile.txt", 'a') # open for writing, appending to the end of file >>> f = open("C:\MyApp.exe", 'b') # open in binary mode for read >>> f = open("C:\myimage.jpg", 'rb') # open file in binary mode for read and write >>> f = open("C:\MyFile.txt", 't') # open in text mode for read >>> f = open("C:\MyFile.txt", mode='r', encoding='utf-8') # open for reading with utf-8 encoding >>> f = open("C:\MyFile.txt", '+') # open for reading or writing >>> print(type(f) >>> f.close() # closing file after file operations Python File Open
Assume we have the following file, located in the same folder as Python:
To open the file, use the built-in open() function.
The open() function returns a file object, which has a read() method for reading the content of the file:
Example
If the file is located in a different location, you will have to specify the file path, like this:
Example
Open a file on a different location:
Read Only Parts of the File
By default the read() method returns the whole text, but you can also specify how many characters you want to return:
Example
Return the 5 first characters of the file:
Read Lines
You can return one line by using the readline() method:
Example
Read one line of the file:
By calling readline() two times, you can read the two first lines:
Example
Read two lines of the file:
By looping through the lines of the file, you can read the whole file, line by line:
Example
Loop through the file line by line:
Close Files
It is a good practice to always close the file when you are done with it.
Example
Close the file when you are finish with it:
Note: You should always close your files, in some cases, due to buffering, changes made to a file may not show until you close the file.
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