升压multi_index例如:错误:无效的操作数为二进制表达
问题描述:
只是想出来的基本boost::multi_index
例子,接收和错误:升压multi_index例如:错误:无效的操作数为二进制表达
#include <boost/multi_index_container.hpp>
#include <boost/multi_index/ordered_index.hpp>
#include <boost/multi_index/identity.hpp>
#include <boost/multi_index/member.hpp>
using namespace boost::multi_index;
struct employee
{
int id;
std::string name;
employee(int id, const std::string &name) : id(id), name(name) {}
bool operator<(const employee &e) const { return id < e.id; }
};
// define a multiply indexed set with indices by id and name
typedef multi_index_container<
employee,
indexed_by<
// sort by employee::operator<
ordered_unique<identity<employee> >,
// sort by less<string> on name
ordered_non_unique<member<employee, std::string, &employee::name> > > >
employee_set;
void print_out_by_name(const employee_set &es)
{
// get a view to index #1 (name)
const employee_set::nth_index<1>::type &name_index = es.get<1>();
// use name_index as a regular std::set
std::copy(
name_index.begin(), name_index.end(),
std::ostream_iterator<employee>(std::cout)); // Looks like the problem is here.
}
收到此错误:
/Library/Developer/CommandLineTools/usr/bin/../include/c++/v1/iterator:813:28: error: invalid operands to binary expression ('ostream_type' (aka
'basic_ostream<char, std::__1::char_traits<char> >') and 'const employee')
*__out_stream_ << __value_;
答
似乎需要一个实现:
std::ostream &operator<<(std::ostream &os, const employee &obj)
{
os << obj.id << "/" << obj.name;
return os;
}
[完整示例](http://www.boost.org/doc/libs/release/libs/mul ti_index/example/basic.cpp)为'employee'实现'operator Praetorian
@Praetorian没有看到。我会检查出来。谢谢 – BAR