character-bag — a sequence containing characters.

string — a string designator.

trimmed-string — a string.

string-trim returns a substring of string, with all characters in character-bag stripped off the beginning and end. string-left-trim is similar but strips characters off only the beginning; string-right-trim strips off only the end.

If no characters need to be trimmed from the string, then either string itself or a copy of it may be returned, at the discretion of the implementation.

All of these functions observe the fill pointer.

 (string-trim "abc" "abcaakaaakabcaaa") → "kaaak" 
 (string-trim '(#\Space #\Tab #\Newline) " garbanzo beans 
        ") → "garbanzo beans" 
 (string-trim " (*)" " ( *three (silly) words* ) ") 
→ "three (silly) words" 

 (string-left-trim "abc" "labcabcabc") → "labcabcabc" 
 (string-left-trim " (*)" " ( *three (silly) words* ) ") 
→ "three (silly) words* ) " 

 (string-right-trim " (*)" " ( *three (silly) words* ) ") 
→ " ( *three (silly) words"

The implementation.