Regex to allow apostrophe only in words ending with 's

Question

I'm reading some files and I need to remove all the apostrophes in the strings except the ones in words ending with 's.

Examples:

Frank's blue car -> Frank's blue car

Frank 'blue' car -> Frank blue car

'Frank's blue car -> Frank's blue car

Frank's' blue 'car -> Frank's blue car

'Frank blue car' -> Frank blue car

Frank'blue'car -> Frankbluecar

Thanks in advance for your help!

EDIT: Modified question since I just need the words ending with 's to keep the apostrophe and not only the singular possessive ones.

Answer 1

So basically you want to disallow apostrophes that aren't surrounded by letters on both sides. You can try the following:

/(?<![a-z])'|'(?!s\b)/i

Replace anything that matches that with an empty string. If you want to allow some contractions also, you can broaden it a bit:

/(?<![a-z])'|'(?![a-z]\b)/i

This pattern matches your requirements, but I offer some notes of caution:

• It will block 'tis and 'twas, which are valid English.
• The first pattern will block most contractions, such as didn't.
• Without an English dictionary database, it will be impossible to distinguish between the singular-possessive (e.g. Frank's) and contractions ending in S (e.g. she's).
• Finally, remember that this will block most plural-possessives as well. This phrase is correct English, but it will still be blocked:

  the kids' toys