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; limit and noerror are set to nil, and repeat is set to 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. See section 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.

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