Trim whitespace from middle of string

Question

I'm using the following regex to capture a fixed width "description" field that is always 50 characters long:

(?.{50})

My problem is that the descriptions sometimes contain a lot of whitespace, e.g.

"FLUID        COMPRESSOR                          "

Can somebody provide a regex that:

1. Trims all whitespace off the end
2. Collapses any whitespace in between words to a single space

Answer 1

str = Regex.Replace(str, " +( |$)", "$1");