Python File truncate() Method

Last Updated : 12 Dec, 2019

Prerequisites:

Truncate() method truncate the file’s size. If the optional size argument is present, the file is truncated to (at most) that size. The size defaults to the current position. The current file position is not changed. Note that if a specified size exceeds the file’s current size, the result is platform-dependent: possibilities include that the file may remain unchanged, increase to the specified size as if zero-filled, or increase to the specified size with undefined new content.
To truncate the file, you can open the file in append mode or write mode.

Syntax:

  fileObject.truncate(size)

Example:
See the below image for file size.

Python-truncate-input

Let’s change the file size to 100 bytes.

   # Python program to demonstrate 
# truncate() method 
  
fp = open('file1.txt', 'w') 
  
# Truncates the file to specified 
# size 
fp.truncate(100) 
  
# Closing files 
fp.close() 
 
  

Output:

python-truncate-output

With statement

In the above approaches, every time the file is opened it is needed to be closed explicitly. If one forgets to close the file, it may introduce several bugs in the code, i.e. many changes in files do not go into effect until the file is properly closed. To prevent this with statement can be used. with statement in Python is used in exception handling to make the code cleaner and much more readable. It simplifies the management of common resources like file streams. Observe the following code example on how the use of with statement makes code cleaner. There is no need to call file.close() when using with statement. The with statement itself ensures proper acquisition and release of resources.

Let’s change the above file to 50 bytes

   # Python program to demonstrate 
# truncate method using with statement 
  
with open('file1.txt', 'w') as fp: 
    fp.truncate(50)

Output:
python-truncate-output

Note: To know more about with statement click here.

Python | os.truncate() method

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