A size of a data that actually was read

Question

I read a part of a file:

size_to_read = 999999
with open(file_name, "r") as f:
  read_part = f.read(size_to_read)

How do I know the size of a data (read_part) that actually was read in case if a size of a file is less than size_to_read?

http://stackoverflow.com/questions/519633/lazy-method-for-reading-big-file-in-python — Denis, Aug 16 '13 at 05:37

DeltaBurnt · Accepted Answer · 2013-08-16T05:56:32.100

3

Simply check the length of the string with the built in len function:

size_to_read = 999999  
with open(file_name, "r") as f:  
  read_part = f.read(size_to_read)  
  if(not len(read_part) == size_to_read):
    eol_reached_unexpectedly()

edited Aug 16 '13 at 05:56

answered Aug 16 '13 at 05:29

DeltaBurnt

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4

1

Technically, if file size is exactly `size_to_read` then your code won't call `eol_reached` while actually you have read all data. – kriomant Aug 16 '13 at 05:34
Forgot about the `!=` operator? – user2357112 Aug 16 '13 at 06:43

score 0 · Answer 2 · answered Aug 16 '13 at 06:13

0

How about using f.tell() and comparing the result to size_to_read?

answered Aug 16 '13 at 06:13

Kimvais

38,306
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108
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A size of a data that actually was read

2 Answers2