how to create regular expression in python

Question

Regular expression for removing all lines between #if X and #endif //#if X Note the C style comment is important and needs to be taken into account

#if X
....
.....
#endif //#if X

The following is not giving desired o/p: So is the re right ?

re.compile("#if.*?#endif //#if X", re.MULTILINE + re.DOTALL)

What is the problem ("not the desired o/p" is rather vague)? — Tim Pietzcker
– Tim Pietzcker, Commented Mar 28, 2011 at 13:40

Tim Pietzcker · Accepted Answer · 2011-03-28 11:36:56Z

2

So far, you have just compiled your regex, you haven't done anything with it yet.

You need to do this:

myregex = re.compile(r"#if.*?#endif //#if X", re.DOTALL)
result = myregex.sub("", subject)

where subject is the string you want to work on (and "" is the replacement string).

You don't need the re.MULTILINE parameter since you're not using the start-/end-of-line anchors at all.

answered Mar 28, 2011 at 11:36

Tim Pietzcker

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reflog · Accepted Answer · 2011-03-28 11:19:46Z

1

Instead of 're.MULTILINE + re.DOTALL' try 're.MULTILINE | re.DOTALL' , it's a bit field

answered Mar 28, 2011 at 11:19

reflog

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1 Comment

Tim Pietzcker Over a year ago

Although that shouldn't matter here because all the flags are powers of 2, so adding and "oring" them will yield the same result. You're still right, though.

Kambus · Accepted Answer · 2011-03-28 11:48:48Z

1

re.compile(r'#if\s+([A-Z]+)$.+?#endif\s+//\s*#if\s+\1', re.M | re.S)

answered Mar 28, 2011 at 11:48

Kambus

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