Tutorial :Why is it recommended to have empty line in the end of file?



Question:

Some code style tools recommend this and I remember seeing some unix command line tools warning about missing empty line.

What is the reasoning for having an extra empty line?


Solution:1

Many older tools misbehave if the last line of data in a text file is not terminated with a newline or carriage return / new line combination. They ignore that line as it is terminated with ^Z (eof) instead.


Solution:2

Apart from the fact that it is a nicer cursor position when you move to the end of a file in a text editor.

Having a newline at the end of the file provides a simple check that the file has not been truncated.


Solution:3

If you try to concatenate two text files together, you will be much happier if the first one ends with a newline character.


Solution:4

An argument can also be made for cleaner diffs if you append to the file following the same reasoning as Why does Python allow a trailing comma in list?


Solution:5

The empty line in the end of file appears so that standard reading from the input stream will know when to terminate the read, usually returns EOF to indicate that you have reached the end. The majority of languages can handle the EOF marker. It is there for that reason from the old days, under DOS, the EOF marker was F6 key or Ctrl-Z, for *nix systems, it was Ctrl-D.

Most, if not all, will actually read right up to the EOF marker so that the runtime library's function of reading from input will know when to stop reading any further. When you open the stream for Append mode, it will wipe the EOF marker and write past it, until a close is explicitly called in which it will insert the EOF marker at that point.

Older tools were expecting a empty line followed by EOF marker. Nowadays, tools can handle the empty line and ignore it.


Solution:6

Also when you modify file and appends some code at the end of file - diff (at least git diff in standard coniguration) will show that you changed the last line, while the only thing you've actually done - added a newline symbol. So cvs reports become less convenient.


Solution:7

Some languages define their input file in terms of input lines, where each input line is a series of characters terminated by a carriage return. If their grammar is so defined, then the last valid line of the file must be terminated by a carriage return too.


Solution:8

It's because of the definition of what a text file is. When you create a new text file in any unix environment, the contents of that file is the new line character '\n'

Without this, the file isn't really identified as a text file. Now once we add code to this text file, its about not removing this initial new line that defines a text file itself.


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