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(elisp)String Search

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Searching for Strings
=====================

   These are the primitive functions for searching through the text in a
buffer.  They are meant for use in programs, but you may call them
interactively.  If you do so, they prompt for the search string; the
arguments LIMIT and NOERROR are `nil', and REPEAT is 1.

   These search functions convert the search string to multibyte if the
buffer is multibyte; they convert the search string to unibyte if the
buffer is unibyte.  Note: Text Representations.

 - Command: search-forward string &optional limit noerror repeat
     This function searches forward from point for an exact match for
     STRING.  If successful, it sets point to the end of the occurrence
     found, and returns the new value of point.  If no match is found,
     the value and side effects depend on NOERROR (see below).

     In the following example, point is initially at the beginning of
     the line.  Then `(search-forward "fox")' moves point after the last
     letter of `fox':

          ---------- Buffer: foo ----------
          -!-The quick brown fox jumped over the lazy dog.
          ---------- Buffer: foo ----------
          
          (search-forward "fox")
               => 20
          
          ---------- Buffer: foo ----------
          The quick brown fox-!- jumped over the lazy dog.
          ---------- Buffer: foo ----------

     The argument LIMIT specifies the upper bound to the search.  (It
     must be a position in the current buffer.)  No match extending
     after that position is accepted.  If LIMIT is omitted or `nil', it
     defaults to the end of the accessible portion of the buffer.

     What happens when the search fails depends on the value of
     NOERROR.  If NOERROR is `nil', a `search-failed' error is
     signaled.  If NOERROR is `t', `search-forward' returns `nil' and
     does nothing.  If NOERROR is neither `nil' nor `t', then
     `search-forward' moves point to the upper bound and returns `nil'.
     (It would be more consistent now to return the new position of
     point in that case, but some existing programs may depend on a
     value of `nil'.)

     If REPEAT is supplied (it must be a positive number), then the
     search is repeated that many times (each time starting at the end
     of the previous time's match).  If these successive searches
     succeed, the function succeeds, moving point and returning its new
     value.  Otherwise the search fails.

 - Command: search-backward string &optional limit noerror repeat
     This function searches backward from point for STRING.  It is just
     like `search-forward' except that it searches backwards and leaves
     point at the beginning of the match.

 - Command: word-search-forward string &optional limit noerror repeat
     This function searches forward from point for a "word" match for
     STRING.  If it finds a match, it sets point to the end of the
     match found, and returns the new value of point.

     Word matching regards STRING as a sequence of words, disregarding
     punctuation that separates them.  It searches the buffer for the
     same sequence of words.  Each word must be distinct in the buffer
     (searching for the word `ball' does not match the word `balls'),
     but the details of punctuation and spacing are ignored (searching
     for `ball boy' does match `ball.  Boy!').

     In this example, point is initially at the beginning of the
     buffer; the search leaves it between the `y' and the `!'.

          ---------- Buffer: foo ----------
          -!-He said "Please!  Find
          the ball boy!"
          ---------- Buffer: foo ----------
          
          (word-search-forward "Please find the ball, boy.")
               => 35
          
          ---------- Buffer: foo ----------
          He said "Please!  Find
          the ball boy-!-!"
          ---------- Buffer: foo ----------

     If LIMIT is non-`nil' (it must be a position in the current
     buffer), then it is the upper bound to the search.  The match
     found must not extend after that position.

     If NOERROR is `nil', then `word-search-forward' signals an error
     if the search fails.  If NOERROR is `t', then it returns `nil'
     instead of signaling an error.  If NOERROR is neither `nil' nor
     `t', it moves point to LIMIT (or the end of the buffer) and
     returns `nil'.

     If REPEAT is non-`nil', then the search is repeated that many
     times.  Point is positioned at the end of the last match.

 - Command: word-search-backward string &optional limit noerror repeat
     This function searches backward from point for a word match to
     STRING.  This function is just like `word-search-forward' except
     that it searches backward and normally leaves point at the
     beginning of the match.