Truncate method #80459

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1. CavadSalmanov commented on Mar 13, 2019

   

   CavadSalmanovmannequin

   on Mar 13, 2019

   MannequinAuthor

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   I created a new file for researching truncate() method. and I writed this text:
   alma
   armud
   heyva
   nar
   qarpiz
   yemis

   I wanted to delete all the text apart from first line by truncate method.

   I writed these codes on python idle:
   __________________________________________
   #First, I read text for showing it's content
   >>> dosya = open('deneme.txt','r')
   >>> dosya.read()
   'alma\narmud\nheyva\nnar\nqarpiz\nyemis'
   >>> dosya.close()
   
   
   #Then writing codes for operation which I wanted
   >>> dosya = open('deneme.txt','r+')
   >>> dosya.readline()
   'alma\n'
   >>> dosya.tell()
   6
   >>> dosya.truncate()
   38
   >>> dosya.seek(0)
   0
   >>> dosya.read()
   'alma\narmud\nheyva\nnar\nqarpiz\nyemis'
   >>> dosya.close()
   #I thought I must closed the file, then read again:
   
   
   #Then I saw nothing has changed
   >>> dosya = open('deneme.txt','r')
   >>> dosya.read()
   'alma\narmud\nheyva\nnar\nqarpiz\nyemis'
   >>> dosya.close()
   
   #But when I writed codes in this way, it is worked
   >>> dosya = open('deneme.txt','r+')
   >>> dosya.readline()
   'alma\n'
   >>> dosya.tell()
   6
   >>> dosya.seek(6)
   6
   >>> dosya.truncate()
   6
   >>> dosya.close()
   >>> dosya = open('deneme.txt','r')
   >>> dosya.read()
   'alma\n'

   # I was on 6th byte in both. But it is worked which I used seek() #method. I think both of them were returnden same things
2. CavadSalmanov

   added

   3.7 (EOL)end of lifeend of life

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Mar 13, 2019
3. tirkarthi commented on Mar 13, 2019

   

   tirkarthi

   on Mar 13, 2019

   Member

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   This looks like a similar report to bpo-26158 where truncate refers to the position of the underlying buffer and could be documented better.
4. MojoVampire

   closed this as completedon Mar 13, 2019
5. ezio-melotti

   transferred this issue fromon Apr 10, 2022