Josue Gomes wrote:

Hi,

Can transform_iterator be used in conjunction with remove_if algorithm? The compiler (vc7.1, vc8, g++) is refusing to compile this:

#include <string> #include <utility> #include <vector> #include <functional> #include <cassert> #include <iostream> #include <boost/iterator/transform_iterator.hpp>

std::vector<std::pair<std::string, int> > c;

struct to_num { typedef int result_type;

int operator()(const std::pair<std::string, int>& p) const { return p.second; } };

int main() { using std::make_pair;

c.push_back(make_pair("A", 2)); c.push_back(make_pair("A", 3)); c.push_back(make_pair("A", 4));

c.push_back(make_pair("A", 15)); c.push_back(make_pair("A", 16)); c.push_back(make_pair("A", 17)); assert(c.size() == 6);

std::remove_if( boost::make_transform_iterator(c.begin(), to_num()), boost::make_transform_iterator(c.end(), to_num()), std::bind1st(std::less_equal<int>(), 10));

Are you sure that you want this, even if it did compile? If you apply remove_if+transform_iterator on: A, 2 B, 3 C, 4 D, 15 E, 16 F, 17 you'll get A, 15 B, 16 C, 17 D, -- E, -- F, -- where -- denotes an unspeficied value. If this is the desired result, try struct to_num { typedef int & result_type; int & operator()(std::pair<std::string, int>& p) const { return p.second; } }; If, on the other hand, you want D, 15 E, 16 F, 17 --, -- --, -- --, -- you don't need transform_iterator at all: std::remove_if( c.begin(), c.end(), boost::bind( std::less_equal<int>(), boost::bind( to_num(), _1 ), 10 ) ); (with the original to_num). You can also use &std::pair<std::string, int>::second instead of to_num() and <= 10 instead of less_equal: boost::bind( to_num(), _1 ) <= 10 or boost::bind( &std::pair<std::string, int>::second, _1 ) <= 10