[EMAIL PROTECTED] wrote:
> pat = re.compile(r"%s" %(userinput) ) #userinput is passed from
> command line argument
that r"%s" % (userinput) thing is a pointless operation: the "r" prefix
controls how backslashes in a string literal is parsed; the result is an
ordinary string ("%s" in this case).
in other words,
pat = re.compile(r"%s" % (userinput))
is just a slightly convoluted way to write
pat = re.compile(str(userinput))
and since you know that userinput is a string (at least if you got it
from sys.argv), you might as well write
pat = re.compile(userinput)
> if the user key in a pattern , eg [-] , and my script will search some
> lines that contains [-]
>
> pat.findall(lines)
>
> but the script produce some error: sre_constants.error: unexpected end
> of regular expression
for what pattern? "[-]" is a valid regular expression (it matches a
single minus), but e.g. "[-" is invalid. to deal with this, catch the
exception:
try:
pat = re.compile(userinput)
except re.error:
print "invalid regular expression:", userinput
sys.exit()
hope this helps!
</F>
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