8.3. Text files and lines¶
A text file can be thought of as a sequence of lines, much like a Python string can be thought of as a sequence of characters. For example, this is a sample of a text file which records mail activity from various individuals in an open source project development team:
From email@example.com Sat Jan 5 09:14:16 2008 Return-Path: <firstname.lastname@example.org> Date: Sat, 5 Jan 2008 09:12:18 -0500 To: email@example.com From: firstname.lastname@example.org Subject: [sakai] svn commit: r39772 - content/branches/ Details: http://source.sakaiproject.org/viewsvn/?view=rev&rev=39772 ...
The entire file of mail interactions is available from
and a shortened version of the file is available from
These files are in a standard format for a file containing multiple mail messages. The lines which start with “From ” separate the messages and the lines which start with “From:” are part of the messages. For more information about the mbox format, see https://en.wikipedia.org/wiki/Mbox.
To break the file into lines, there is a special character that represents the “end of the line” called the newline character.
In Python, we represent the newline character as a
backslash-n in string constants. Even though this looks like two
characters, it is actually a single character. When we look at the
variable by entering “stuff” in the interpreter, it shows us the
the string, but when we use
You can also see that the length of the string
X\nY is three
characters because the newline character is a single character.
So when we look at the lines in a file, we need to remember that there is a special invisible character called the newline at the end of each line that marks the end of the line.
So the newline character separates the characters in the file into lines.