php - With word boundaries () in RegEx do I need to have it before AND after the word, or just before?

Question

If I want to match all occurrences of the word foo would I use foo or without the last one? It seems both work, but what's proper?

Answer 1

You would need to use both. Without the last you would get a match on strings such as:

"I love football"
"You foolishly left off your second word boundary"