http://hg.python.org/cpython/rev/3958121a027f changeset: 75342:3958121a027f branch: 2.7 parent: 75339:fc89e09ca2fc user: Ezio Melotti <ezio.melotti@gmail.com> date: Wed Feb 29 13:37:07 2012 +0200 summary: #14155: remove duplication about search vs match in re doc. files: Doc/library/re.rst | 81 ++++++++++++--------------------- 1 files changed, 29 insertions(+), 52 deletions(-) diff --git a/Doc/library/re.rst b/Doc/library/re.rst --- a/Doc/library/re.rst +++ b/Doc/library/re.rst @@ -400,31 +400,6 @@ three digits in length. -.. _matching-searching: - -Matching vs Searching ---------------------- - -.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org> - - -Python offers two different primitive operations based on regular expressions: -**match** checks for a match only at the beginning of the string, while -**search** checks for a match anywhere in the string (this is what Perl does -by default). - -Note that match may differ from search even when using a regular expression -beginning with ``'^'``: ``'^'`` matches only at the start of the string, or in -:const:`MULTILINE` mode also immediately following a newline. The "match" -operation succeeds only if the pattern matches at the start of the string -regardless of mode, or at the starting position given by the optional *pos* -argument regardless of whether a newline precedes it. - - >>> re.match("c", "abcdef") # No match - >>> re.search("c", "abcdef") # Match - <_sre.SRE_Match object at ...> - - .. _contents-of-module-re: Module Contents @@ -547,10 +522,11 @@ Return ``None`` if the string does not match the pattern; note that this is different from a zero-length match. - .. note:: + Note that even in :const:`MULTILINE` mode, :func:`re.match` will only match + at the beginning of the string and not at the beginning of each line. - If you want to locate a match anywhere in *string*, use :func:`search` - instead. + If you want to locate a match anywhere in *string*, use :func:`search` + instead (see also :ref:`search-vs-match`). .. function:: split(pattern, string, maxsplit=0, flags=0) @@ -746,16 +722,14 @@ The optional *pos* and *endpos* parameters have the same meaning as for the :meth:`~RegexObject.search` method. - .. note:: - - If you want to locate a match anywhere in *string*, use - :meth:`~RegexObject.search` instead. - >>> pattern = re.compile("o") >>> pattern.match("dog") # No match as "o" is not at the start of "dog". >>> pattern.match("dog", 1) # Match as "o" is the 2nd character of "dog". <_sre.SRE_Match object at ...> + If you want to locate a match anywhere in *string*, use + :meth:`~RegexObject.search` instead (see also :ref:`search-vs-match`). + .. method:: RegexObject.split(string, maxsplit=0) @@ -1121,37 +1095,39 @@ being recast as ``Begin [a-zA-Z0-9_ ]*?end``. As a further benefit, such regular expressions will run faster than their recursive equivalents. +.. _search-vs-match: search() vs. match() ^^^^^^^^^^^^^^^^^^^^ -In a nutshell, :func:`match` only attempts to match a pattern at the beginning -of a string where :func:`search` will match a pattern anywhere in a string. -For example: +.. sectionauthor:: Fred L. Drake, Jr. <fdrake@acm.org> - >>> re.match("o", "dog") # No match as "o" is not the first letter of "dog". - >>> re.search("o", "dog") # Match as search() looks everywhere in the string. +Python offers two different primitive operations based on regular expressions: +:func:`re.match` checks for a match only at the beginning of the string, while +:func:`re.search` checks for a match anywhere in the string (this is what Perl +does by default). + +For example:: + + >>> re.match("c", "abcdef") # No match + >>> re.search("c", "abcdef") # Match <_sre.SRE_Match object at ...> -.. note:: +Regular expressions beginning with ``'^'`` can be used with :func:`search` to +restrict the match at the beginning of the string:: - The following applies only to regular expression objects like those created - with ``re.compile("pattern")``, not the primitives ``re.match(pattern, - string)`` or ``re.search(pattern, string)``. + >>> re.match("c", "abcdef") # No match + >>> re.search("^c", "abcdef") # No match + >>> re.search("^a", "abcdef") # Match + <_sre.SRE_Match object at ...> -:func:`match` has an optional second parameter that gives an index in the string -where the search is to start:: +Note however that in :const:`MULTILINE` mode :func:`match` only matches at the +beginning of the string, whereas using :func:`search` with a regular expression +beginning with ``'^'`` will match at the beginning of each line. - >>> pattern = re.compile("o") - >>> pattern.match("dog") # No match as "o" is not at the start of "dog." - - # Equivalent to the above expression as 0 is the default starting index: - >>> pattern.match("dog", 0) - - # Match as "o" is the 2nd character of "dog" (index 0 is the first): - >>> pattern.match("dog", 1) + >>> re.match('X', 'A\nB\nX', re.MULTILINE) # No match + >>> re.search('^X', 'A\nB\nX', re.MULTILINE) # Match <_sre.SRE_Match object at ...> - >>> pattern.match("dog", 2) # No match as "o" is not the 3rd character of "dog." Making a Phonebook -- Repository URL: http://hg.python.org/cpython