Double vs. single quotes using formatted printing in python

Question

So I was going through "Learn Python the Hard Way"

and while doing this:

formatter = "%r %r %r %r"

print formatter % (
    "I had this thing.",
    "That you could up right.",
    "But it didn't sing.",
    "So I said goodnight"
)

the output was

'I had this thing.' 'That you could up right.' "But it didn't sing." 'So I said goodnight'

But I'm not sure why the 3rd string has double strings.

Answer 1

"a" and 'a' are the same strings, no difference.

The third string contains an apostrophe, so it cannot be represented as 'But it didn't sing.' because that would end the string after didn and raise a SyntaxError.

If you want to represent a string with single quote, you can do it:

"'"

or

'\''

The same with double quote:

'"'

or

"\""

If you have a string with both quotes, you can choose one:

'"\'"

or

"\"'"