Question

我试图通过一些例子来学习boost :: iostreams。以下是其中一个gcc无法接受的内容：

#include <iostream>
#include <boost/iostreams/filter/regex.hpp>
#include <boost/iostreams/copy.hpp>
#include <boost/iostreams/filtering_stream.hpp>
#include <boost/iostreams/device/back_inserter.hpp>

using namespace std;

int main()
{
    boost::regex reg("a.c");    
    string str("abcdef aochijk");   
    string result;
    boost::iostreams::copy(
                boost::make_iterator_range(str),    
                boost::iostreams::filtering_ostream(    
                    boost::iostreams::regex_filter(reg,"test") |    
                    boost::iostreams::back_inserter(result))    
                );
    cout<<result<<endl; 
    return 0;
}

以下是错误：

error:no matching function for call to 'copy(boost::iterator_range<__gnu_cxx::__normal_iterator<char*, std::basic_string<char> > >, boost::iostreams::filtering_ostream)'

error:no type named 'type' in 'struct boost::disable_if<boost::iostreams::is_std_io<boost::iostreams::filtering_stream<boost::iostreams::output> >, void>'

Answer 1

我的clang副本也无法编译，告诉我note: candidate function [snip] not viable: expects an l-value for 2nd argument。

这对我来说似乎很合理，事实上，这会编译：

boost::regex reg("a.c");    
string str("abcdef aochijk");
string result;
boost::iostreams::filtering_ostream ios(    
                boost::iostreams::regex_filter(reg,"test") |    
                boost::iostreams::back_inserter(result));
boost::iostreams::copy( boost::make_iterator_range(str), ios);

Answer 2

#include <iostream>
#include <boost/iostreams/filter/regex.hpp>
#include <boost/iostreams/copy.hpp>
#include <boost/iostreams/filtering_stream.hpp>
#include <boost/iostreams/device/back_inserter.hpp>

using namespace std;

int main()
{
    boost::regex reg("a.c");    
    string str("abcdef aochijk");   
    string result;
    boost::iostreams::filtering_ostream fos(boost::iostreams::regex_filter(reg,"test") |    
                                            boost::iostreams::back_inserter(result))   ;
    boost::iostreams::copy(boost::make_iterator_range(str),fos);
    cout<<result<<endl; 
    return 0;
}

在boost :: iostreams :: copy上编译错误

2 个答案: