# Diff of /code/trunk/doc/html/pcrematching.html

revision 571 by ph10, Sat Nov 6 17:10:00 2010 UTC revision 572 by ph10, Wed Nov 17 17:55:57 2010 UTC
# Line 106  The scan continues until either the end Line 106  The scan continues until either the end
106  no more unterminated paths. At this point, terminated paths represent the  no more unterminated paths. At this point, terminated paths represent the
107  different matching possibilities (if there are none, the match has failed).  different matching possibilities (if there are none, the match has failed).
108  Thus, if there is more than one possible match, this algorithm finds all of  Thus, if there is more than one possible match, this algorithm finds all of
109  them, and in particular, it finds the longest. There is an option to stop the  them, and in particular, it finds the longest. The matches are returned in
110  algorithm after the first match (which is necessarily the shortest) is found.  decreasing order of length. There is an option to stop the algorithm after the
111    first match (which is necessarily the shortest) is found.
112  </P>  </P>
113  <P>  <P>
114  Note that all the matches that are found start at the same point in the  Note that all the matches that are found start at the same point in the
115  subject. If the pattern  subject. If the pattern
116  <pre>  <pre>
117    cat(er(pillar)?)    cat(er(pillar)?)?
118  </pre>  </pre>
119  is matched against the string "the caterpillar catchment", the result will be  is matched against the string "the caterpillar catchment", the result will be
120  the three strings "cat", "cater", and "caterpillar" that start at the fourth  the three strings "caterpillar", "cater", and "cat" that start at the fifth
121  character of the subject. The algorithm does not automatically move on to find  character of the subject. The algorithm does not automatically move on to find
122  matches that start at later positions.  matches that start at later positions.
123  </P>  </P>
# Line 185  callouts. Line 186  callouts.
186  2. Because the alternative algorithm scans the subject string just once, and  2. Because the alternative algorithm scans the subject string just once, and
187  never needs to backtrack, it is possible to pass very long subject strings to  never needs to backtrack, it is possible to pass very long subject strings to
188  the matching function in several pieces, checking for partial matching each  the matching function in several pieces, checking for partial matching each
189  time. It is possible to do multi-segment matching using <b>pcre_exec()</b> (by  time. Although it is possible to do multi-segment matching using the standard
190  retaining partially matched substrings), but it is more complicated. The  algorithm (<b>pcre_exec()</b>), by retaining partially matched substrings, it is
191    more complicated. The
192  <a href="pcrepartial.html"><b>pcrepartial</b></a>  <a href="pcrepartial.html"><b>pcrepartial</b></a>
193  documentation gives details of partial matching and discusses multi-segment  documentation gives details of partial matching and discusses multi-segment
194  matching.  matching.
# Line 218  Cambridge CB2 3QH, England. Line 220  Cambridge CB2 3QH, England.
220  </P>  </P>
221  <br><a name="SEC8" href="#TOC1">REVISION</a><br>  <br><a name="SEC8" href="#TOC1">REVISION</a><br>
222  <P>  <P>
223  Last updated: 22 October 2010  Last updated: 17 November 2010
224  <br>  <br>
225  Copyright &copy; 1997-2010 University of Cambridge.  Copyright &copy; 1997-2010 University of Cambridge.
226  <br>  <br>

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