Using boost::lexical_cast with std::transform

Question

g++ doesn't like:

vector<int> x;
x += 1,2,3,4,5;

vector<string> y(x.size());
transform(x.begin(), x.end(), y.begin(), lexical_cast<string>);

The error message is:

error: no matching function for call to 'transform(__gnu_cxx::__normal_iterator<int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<int*, std::vector<int, std::allocator<int> > >, __gnu_cxx::__normal_iterator<std::basic_string<char, std::char_traits<char>, std::allocator<char> >*, std::vector<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > >, <unresolved overloaded function type>)'

Which clearly indicates there is an issue with lexical_cast as the last argument to transform... Is there a way to avoid writing a function object that wraps lexical_cast?

Thanks!

Strychnic

Off the top of my head, you probably need lexical_cast<string, int> since there is no argument deduction for the second template argument. lexical_cast might be overloaded, though, which would then require you to use a cast to disambiguate which one you want. – Gavra

Answer 1

This is untested, but you could try:

transform(x.begin(), x.end(), y.begin(), lexical_cast<string, int>);

lexical_cast is a template with two template parameters. Normally the second one is deduced from type deduction from the argument, but you aren't providing an argument, so you need to explicitly specify it.

Senghor

Makes sense. I should have seen that. Thanks! – Strychnic