c – boost :: format和定制打印std容器

template <typename T>
std::ostream& operator<<(std::ostream& stream,const std::set<T>& set)
{
    stream << "{";
    bool first = true;
    for (const T& item : set)
    {
        if (!first)
            stream << ",";
        else
            first = false;
        stream << item;
    }
    stream << "}";
    return stream;
}

std::set<std::string> x = { "1","2","3","4" };
std::cout << x << std::endl;

std::set<std::string> x = { "1","4" };
boost::format("%1%") % x;

我认为最干净的方法是为您要覆盖的每个操作符在您自己的命名空间中提供一个薄的包装器.对于你的情况,它可以是：

namespace ns
{
    namespace wrappers
    {
        template<class T>
        struct out
        {
            const std::set<T> &set;

            out(const std::set<T> &set) : set(set) {}

            friend std::ostream& operator<<(std::ostream& stream,const out &o)
            {
                stream << "{";
                bool first = true;
                for (const T& item : o.set)
                {
                    if (!first)
                        stream << ",";
                    else
                        first = false;
                    stream << item;
                }
                stream << "}";
                return stream;
            }
        };
    }

    template<class T>
    wrappers::out<T> out(const std::set<T> &set)
    {
        return wrappers::out<T>(set);
    }
}

然后使用它：

std::cout << boost::format("%1%") % ns::out(X);