Re: adapter function for for_each

From:

Greg Herlihy <greghe@mac.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Thu, 21 Aug 2008 07:28:35 CST

Message-ID:

<8e8da33a-0bd6-4a14-aec5-4e3d99d7e9ec@o40g2000prn.googlegroups.com>

On Aug 20, 3:28 pm, dominolog <dominiktomc...@gmail.com> wrote:

I've got following container:

std::vector<boost::shared_ptr<std::string> > strings;
strings.push_back( boost::shared_ptr<std::string> ( new
std::string("AAA") ) );

....

std::for_each( strings.begin(), strings.end(),
std::mem_fun( &std::length ) );

Now I want a 0-parameter method from std::string to be called on every
element from the sequence. '

The question is - how to construct a correct adapter for it, not using
a custom operand class. I want to use only stl stuff.

Use std::tr1::mem_fn(). For example:

     #include <tr1/memory>
     #include <tr1/functional>
     #include <string>
     #include <vector>
     #include <algorithm>

     using std::string;
     using std::tr1::shared_ptr;
     using std::tr1::mem_fn;

     int main()
     {
         std::vector< shared_ptr<string> > v;

         std::for_each(v.begin(), v.end(), mem_fn(&string::length));
     }

Greg

--
      [ See http://www.gotw.ca/resources/clcm.htm for info about ]
      [ comp.lang.c++.moderated. First time posters: Do this! ]