Content of wchar is deleted

I have this code:

JSONObject object;
if (value->IsObject())
{
    object = value->AsObject();
    const wchar_t *tmp = from_string(entity_id);
    std::wcout << tmp << std::endl;
    std::wcout.flush();
    if (object.find(tmp) != object.end())
    {
        std::wcout << tmp << std::endl;
        std::wcout.flush();
        initFromJSON(object[tmp]->AsObject());
    }
    else
    {
        return false;
    }

}

Problem here is that after inner if statement, the content of a tmp is empty. Before that it's not. When I try debuggin, it's everything ok, the content is not deleted. But when I run program, content is deleted. Any idea why?

Method from_string(entity_id) only convert from string to wchar like this:

std::wstring result;
for (int i = 0; i<content.length(); i++)
    result += wchar_t(content[i]);
return result.c_str();

Methods JSONObject::find(...) and JSONObject::end() are this:

iterator find(const key_type& __k)             {return __tree_.find(__k);}
iterator end() _NOEXCEPT {return __tree_.end();}

I don't believe that is problem in find(...) or in end(). I'm guessing that problem is somewhere else but I cannot locate it. Because the content of wchar is empty after the if statement I cannot say

initFromJSON(object[tmp]->AsObject());

because object[tmp] doesn't exist.

Any advice what am I doing wrong?