I'm getting this string as an input "<operator value=1/>".
How in C can I parse out this string to get the "1" back?
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2That's not a well-formed XML, btw. attribute values should be enclosed in quotes.Mehrdad Afshari– Mehrdad Afshari2009-10-03 21:05:47 +00:00Commented Oct 3, 2009 at 21:05
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might not be xml. Is the string supposed to be a snippet of Xml ? or is it some legacy, like sgml ?Andrew Keith– Andrew Keith2009-10-03 21:12:00 +00:00Commented Oct 3, 2009 at 21:12
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2 Answers
If you know that that's exactly the type of string you'll always get, you can just use sscanf():
int value;
if(sscanf(theString, "<operator value=%d/>", &value) == 1)
; // parsing succeeded, use value
else
; // parsing failed
If you're going to be receiving more complex input, I recommend using an XML parsing library such as expat or TinyXML (requires C++).
4 Comments
goe
But I need to extract the "1". This value may differ from time to time. So the String will look the same but the value can change. Can I still use sscanf to just retrieve whatever is between = and / ?
pmg
If I could I'd give you 1 point extra for checking the return value of sscanf()
Adam Rosenfield
@goe: Yes, if the value you're looking for is an integer, this will accept any integer in place of "1". If you're looking for a string in general, you'll have to something more complex.
goe
so I can't do: sscanf(theString, "<operator value=%s/>", &string)
i am assuming your parsing the string without using any library and the string may not be legal. I once encountered this problem when parsing sgml.
there are a few ways to do this. You could use strstok to split the string to find the value 1, then convert it using atoi.
I would recommend you use a regex library to extract the string. It would handle more boundary cases.
