Match words and ignore numbers with Regex

I have a list of words, for example, "at", "in", "on".
I need to match any of those exact words but I’m having some difficulty with one part of it.

Examples:

"I am at work" – should match with "at"

"I am attracting honey bees" – should not match

"I am at123" – should match

I currently have something like this, but it’s not doing exactly what i need.

(?i)(\W|^)(at|in|on)(\W|$)

Any assistance is appreciated

>Solution :

It appears that you want to match these words when surrounded by either whitespace, numbers, or the start/end of the string. In that case, we can try using the following pattern:

(?:(?<!\S)|(?<!\D))(?:at|in|on)(?:(?!\S)|(?!\D))

This pattern says to:

• (?:
  • (?<!\S) lookbehind and assert whitespace or the start of the string precedes
  • | OR
  • (?<!\D) lookbehind and assert that a digit or the start of the string precedes
• )
• (?:at|in|on) match at, in, or on
• (?:
  • (?!\S) lookahead and assert whitespace or the start of the string follows
  • | OR
  • (?!\D) lookahead and assert that a digit or the start of the string precedes
• )