Python read all text file lines in loop

Question

I want to read huge text file line by line  and stop if a line with  str  found   How to check  if file-end is reached   fn    t log  f   open fn   r   while not  is eof f      how to check that end is reached      s   f readline       print s     if  str  in s  break

User · Answer

You can stop the 2-line separation in the output by using     with open  t ini   as f         for line in f             print line strip              if  str  in line                break

User · Answer

There s no need to check for EOF in python  simply do   with open  t ini   as f     for line in f           For Python3  use print line         print line        if  str  in line            break   Why the with statement      It is good practice to use the with keyword when dealing with file   objects  This has the advantage that the file is properly closed after   its suite finishes  even if an exception is raised on the way

User · Answer

There are situations where you can t use the  quite convincing  with    for    structure  In that case  do the following   line   self fo readline   if len line     0       if  str  in line           break   This will work because the the readline   leaves a trailing newline character  where as EOF is just an empty string

User · Answer

Just iterate over each line in the file  Python automatically checks for the End of file and closes the file for you  using the with syntax    with open  fileName    r   as f      for line in f         if  str  in line             break

[python] Python: read all text file lines in loop

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