How to use for_each from C++ boost library?

问题

I try to use for_each from the C++ boost library. This is the code that I have.

#include <iostream>
#include <vector>

#include <boost/fusion/algorithm/iteration/for_each.hpp>
#include <boost/fusion/include/for_each.hpp>

using namespace std;

int main() {

        vector<int> vec;
        vec.push_back(1);
        vec.push_back(2);
        vec.push_back(3);

         boost::for_each(
                vec,
                [](int val){
                        cout << val << "\n";
                }
        );

        return 0;
}

This is how I compile my code:

g++ -std=c++0x -I /opt/software/boost/1.50_ubuntu12.4lts_gcc4.7.2/include -c try_boost.cpp
g++ -o try_boost -L/opt/software/boost/1.50_ubuntu12.4lts_gcc4.7.2/lib try_boost.o -lboost

As a result I get:

error: ‘for_each’ is not a member of ‘boost’

Does anybody know why it does not work?

回答1:

You're using for_each from Boost.Fusion Library. That doesn't work with std::vector.

The for_each which you need is from Boost.Range Library.

#include <boost/range/algorithm/for_each.hpp> //note this difference!

boost::for_each(vec, your-lambda-expression);

It is defined inside boost::range namespace, which is brought to boost namespace using using declarative. So you can also write this:

boost::range::for_each(vec, your-lambda-expression);

来源：https://stackoverflow.com/questions/15527999/how-to-use-for-each-from-c-boost-library