Question

This seems like such a basic question, so I apologize if it’s already been answered somewhere (my searching didn’t turn up anything).

I just want to filter a string object so that it contains only alphanumeric and space characters.

Here’s what I tried:

#include "boost/algorithm/string/erase.hpp"
#include "boost/algorithm/string/classification.hpp"

std::wstring oldStr = "Bla=bla =&*\nSampleSampleSample ";
std::wstring newStr = boost::erase_all_copy(oldStr, !(boost::is_alnum() || 
                                                      boost::is_space()));

But the compiler is not at all happy with that — it seems that I can only put a string in the second argument of erase_all_copy and not this is_alnum() stuff.

Is there some obvious solution I’m missing here?

Answer 1

With the std algorithms and Boost.Bind:

std::wstring s = ...
std::wstring new_s;
std::locale loc;
std::remove_copy_if(s.begin(), s.end(), std::back_inserter(new_s), 
    !(boost::bind(&std::isalnum<wchar_t>, _1, loc)||
      boost::bind(&std::isspace<wchar_t>, _1, loc)
));