Python open() function

overview of open()

The open() function tries to open the specified file and if successful the corresponding file object is returned. If the file is not found a FileNotFoundError exception is raised.

use of open()

The open() function is most commonly used to overwrite a file or append content at the end of the file. Both variants are shown below. # open in read mode f1 = open('f1.txt') # overwrite content in file f2 = open('f2.txt', 'w') # append content to file f3 = open('f3.txt', 'a') The open mode is specified in the second parameter and the most common values are: 'r' for reading mode, 'w' for writing mode and 'a' for appending mode. The default value is 'r'.

syntax of open()

The syntax of the open() function is: open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, opener=None)

arguments of open()

The open() function accepts up to 8 arguments. The first argument is the filename and it is the only required argument, the following 7 arguments are optional.
argument required description
file required the filename of the file to be opened
mode optional the file mode to use, default value is 'r'
buffering optional the buffering policy, default value is -1
encoding optional the encoding format, default value is None
errors optional defines how to handle errors, default value is None
newline optional defines how newlines are used, default value is None
closefd optional must be True or an exception will be raised, default value is True
opener optional defines a custom opener, default value is None

return value of open()

If the specified file has been opened successfully, the open() function returns the file object. This file object can be used to read, write and modify the file later. Otherwise, if the file is not found, a FileNotFoundError exception is raised.



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