PHP reg expression question

[blaketar]

Simple question, what is the most efficient way to search for whole words in a string?

For example if I have two strings:

1.) This is the way to the lake.
2.) It was always like this.

When I search for the word "is" only the 1st string should match. My current script returns the second string also because it has "this" or i and s in the sequence.

[cameraman]

I wouldn't be surprised if there were a better way, but this looks to be working:
#(^is)¦(\sis\s)¦(\sis$)#i

[coopster]

You could use a word boundary [php.net].

[g1smd]

This would work:

((^is(\ ¦\,¦\.))¦(\ is(\ ¦\,¦\.)))

- Begins with the word and is then followed by a space, comma or period.
- Has a space before, and a space, or comma, or period directly after.