Fix Python – What is the difference between and re.match?


Asked By – Daryl Spitzer

What is the difference between the search() and match() functions in the Python re module?

I’ve read the documentation (current documentation), but I never seem to remember it. I keep having to look it up and re-learn it. I’m hoping that someone will answer it clearly with examples so that (perhaps) it will stick in my head. Or at least I’ll have a better place to return with my question and it will take less time to re-learn it.

Now we will see solution for issue: What is the difference between and re.match?


re.match is anchored at the beginning of the string. That has nothing to do with newlines, so it is not the same as using ^ in the pattern.

As the re.match documentation says:

If zero or more characters at the
beginning of string match the regular expression pattern, return a
corresponding MatchObject instance.
Return None if the string does not
match the pattern; note that this is
different from a zero-length match.

Note: If you want to locate a match
anywhere in string, use search()
instead. searches the entire string, as the documentation says:

Scan through string looking for a
location where the regular expression
pattern produces a match, and return a
corresponding MatchObject instance.
Return None if no position in the
string matches the pattern; note that
this is different from finding a
zero-length match at some point in the

So if you need to match at the beginning of the string, or to match the entire string use match. It is faster. Otherwise use search.

The documentation has a specific section for match vs. search that also covers multiline strings:

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
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.

Now, enough talk. Time to see some example code:

# example code:
string_with_newlines = """something

import re

print re.match('some', string_with_newlines) # matches
print re.match('someother', 
               string_with_newlines) # won't match
print re.match('^someother', string_with_newlines, 
               re.MULTILINE) # also won't match
                string_with_newlines) # finds something
print'^someother', string_with_newlines, 
                re.MULTILINE) # also finds something

m = re.compile('thing$', re.MULTILINE)

print m.match(string_with_newlines) # no match
print m.match(string_with_newlines, pos=4) # matches
               re.MULTILINE) # also matches

This question is answered By – nosklo

This answer is collected from stackoverflow and reviewed by FixPython community admins, is licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0