Python: Regex to match multiline strings in C code

Question

I'm attempting to match multiline strings in C code via the re module.

I'd like to match strings of the form:

char * theString = "Some string \
                   I want to match.";

I tried the following regex, which does not work:

regex = re.compile(r"\".*\"$", re.MULTILINE)

I thought that it would match the first ", then continue searching the next line until it found a closing ", but this is not the case. Is this because $ requires that there be a " at the end of the line to match? Is there some way to do this using regex?

score 1 · Accepted Answer · 2016-01-15 23:25:33Z

1

Use dot all flag.

However, this is the way to parse C strings. (?s)"[^"\\]*(?:\\.[^"\\]*)*"

if it doesn't support (?s) inline modifier, set the modifier in the flags parameter.

re.compile(r'"[^"\\]*(?:\\.[^"\\]*)*"', re.DOTALL)

 (?s)
 "
 [^"\\]*                       # Double quoted text
 (?: \\ . [^"\\]* )*
 "

Ideally, you should add (raw regex) (?<!\\)(?:\\\\)* at the beginning,
to make sure the opening double quote is not escaped.

edited Jan 15, 2016 at 23:25

answered Jan 15, 2016 at 23:04

user557597

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8 Comments

Victor Brunell Over a year ago

@ sln Using that expression in re.compile((?s)"[^"\]*(?:\\.[^"\]*)*") produces a syntax error. Have I used it incorrectly? I'm new to python regex.

user557597 Over a year ago

@VictorBrunell - You could use the raw syntax, or just a normal double quoted string "(?s)\"[^\"\\\\]*(?:\\\\.[^\"\\\\]*)*\"" Is it a language parse syntax error I presume? If its a regex syntax error, it might not like the modifier (?s) in which case take it out and use the DOTALL flag from the options.

Victor Brunell Over a year ago

@ sln re.compile("(?s)\"[^\"\\\\]*(?:\\\\.[^\"\\\\]*)*\"") returns no match as well unfortunately.

user557597 Over a year ago

re.compile(r'"[^"\\]*(?:\\.[^"\\]*)*"', re.DOTALL)

Victor Brunell Over a year ago

@ sln When running that against the lines in my original post via print myregex.findall(line) it still returns [], where myregex = re.compile(r'"[^"\\]*(?:\\.[^"\\]*)*"', re.DOTALL)

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