find-string in text%

Finds an exact-match string in the editor and returns its position. If the string is not found, #f is returned.

• (send a-text find-string str direction start end get-start? case-sensitive?) -> exact non-negative integer or #f
   str : string
     direction = 'forward : symbol in '(forward backward)
   start = 'start : exact non-negative integer or 'start
   end = 'eof : exact non-negative integer or 'eof
   get-start? = #t : boolean
     case-sensitive? = #t : boolean

  The direction argument can be 'forward or 'backward, indicating a forward search or backward search respectively. In the case of a forward search, the return value is the starting position of the string; for a backward search, the ending position is returned. However, if get-start? is #f, then the other end of the string position will be returned.

  The start and end arguments set the starting and ending positions of a forward search (use start > end for a backward search). If start is 'start, then the search starts at the start of the selection. If end is 'eof, then the search continues to the end (for a forward search) or start (for a backward search) of the editor.

  If case-sensitive? is #f, then an uppercase and lowercase of each alphabetic character are treated as equivalent.