Hi, from Japan.I'm pretty new to c++ and I'm trying to work out on regex. When I compile these lines,it ends with "undefined reference to ..." Please let me know how to use regex properly. I use on FC4 and newest boost version,compiling in Anjuta. ****************************** #include <iostream> #include using namespace std; using namespace boost; int main() { const char* re ="[0-9]"; regex expression(re); const char* str= "1234567890"; cmatch what; regex_match(str,what,expression); } *******************************

Hello,Sir and everybody.

Presumably you need to add the -lboost_regex to your linkers command line.

OK,it worked!! Thank you for your advice. I'v change my test program a little. ************************** #include <iostream> #include using namespace std; using namespace boost; int main() { const char* re ="[0-9](.*)"; regex expression(re); const char* str= "1234567890"; cmatch what; regex_match(str,what,expression); cout << "success" < wrote:

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Hi, from Japan.I'm pretty new to c++ and I'm trying to work out on regex. When I compile these lines,it ends with "undefined reference to ..." Please let me know how to use regex properly. I use on FC4 and newest boost version,compiling in Anjuta.

You don't say what compiler you're using? Presumably you need to add the -lboost_regex to your linkers command line.

Note also that [0-9] will only match the first character of "1234567890" so the call to regex_match will fail (regex_match requires that the whole of the text is matched in order to succeed). Use regex_search if you want to match a sub-string of the text.

John.

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Hugh Hoover writes:

On Dec 3, 2005, at 15:44, David Abrahams wrote:

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Hugh Hoover writes:

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I have a need to provide STL compliant iterators from an abstract class A, that is, without knowing the runtime type of the actual "collection" being iterated.. As near as I can tell, these things

<snip>

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Have you looked at boost::indirect_iterator? Just make a container of pointers to the abstract base and iterate over that :)

Thanks for the suggestion, but that won't really work.

Why? -- Dave Abrahams Boost Consulting www.boost-consulting.com

Hugh Hoover writes:

On Dec 6, 2005, at 12:43, David Abrahams wrote:

...

Hugh Hoover writes:

...

On Dec 3, 2005, at 15:44, David Abrahams wrote:

...

Hugh Hoover writes:

...

I have a need to provide STL compliant iterators from an abstract class A, that is, without knowing the runtime type of the actual "collection" being iterated.. As near as I can tell, these things

<snip>

...

Have you looked at boost::indirect_iterator? Just make a container of pointers to the abstract base and iterate over that :)

Thanks for the suggestion, but that won't really work.

Why?

mainly performance. Imagine a tree structure where the nodes are of different concrete types based on a common abstract interface. So far, no problem... But, the nodes have subtree arity ranging from 0 to >10,000 - to walk the structure means creating a new vector for each node visited with a size equal to the node's arity, and initializing from another structure (which may not be a vector).

If I use some kind of abstract iterator interface, the >iterator< gets allocated, but can walk the concrete structure directly. Clearly, there's a tradeoff here - and I'm betting that the abstract iterator is cheaper than the vector - I haven't proven that.

Oh, are you iterating over homogeneous containers of X1,...Xn where every Xi is derived from some common base class, B? If instead you are iterating over containers of heterogeneous derived classes, I can't understand how you can do better than what I proposed. -- Dave Abrahams Boost Consulting www.boost-consulting.com