Regular Express (correct version)

[Anon]

Let's say I have the following string:

$my_string = "rainbow has seven colors";

How can I write a regular expression that

WILL match:
"rainbow"
"seven"
"colors"

but will NOT match:
"rain"
"color"

Thanks in advance!!

[Anon]

how about exploding it by the space and then juust loop through the array testing by something as simple as ==

[Anon]

I'd like to associate this feature with database so I need a fast way of doing it. So I guess I have to use regular expressions.