8.9. Debugging

When you are reading and writing files, you might run into problems with whitespace. These errors can be hard to debug because spaces, tabs, and newlines are normally invisible:

s = '1 2\t 3\n 4' print(s)

The built-in function repr can help. It takes any object as an argument and returns a string representation of the object. For strings, it represents whitespace characters with backslash sequences:

s = '1 2\t 3\n 4' print(repr(s))

This can be helpful for debugging.

One other problem you might run into is that different systems use different characters to indicate the end of a line. Some systems use a newline, represented \n. Others use a return character, represented \r. Some use both. If you move files between different systems, these inconsistencies might cause problems.

Q-4: Which of the following symbols create newlines, or returns, in files? Select all that apply.

• \n
• This is the symbol for a newline.
• \t
• This is the symbol for a tab.
• \r
• This is the symbol for the return character.
• \'
• This is the symbol for the ' character in a string.

For most systems, there are applications to convert from one format to another. You can find them (and read more about this issue) at wikipedia.org/wiki/Newline. Or, of course, you could write one yourself.

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