一个更简单的方法是使用标准复制算法:

#include <iostream>
#include <algorithm> // for copy
#include <iterator> // for ostream_iterator
#include <vector>

int main() {
    /* Set up vector to hold chars a-z */
    std::vector<char> path;
    for (int ch = 'a'; ch <= 'z'; ++ch)
        path.push_back(ch);

    /* Print path vector to console */
    std::copy(path.begin(), path.end(), std::ostream_iterator<char>(std::cout, " "));

    return 0;
}

ostream_iterator被称为迭代器适配器。它被模板化在要打印到流的类型上(在本例中为char)。Cout(又名控制台输出)是我们想要写入的流，空格字符(" ")是我们想要打印在存储在vector中的每个元素之间的内容。

这个标准算法非常强大，其他算法也是如此。标准库提供的强大功能和灵活性使它如此出色。想象一下:您可以用一行代码将一个向量打印到控制台。您不必处理分隔符的特殊情况。您不需要担心for循环。标准库为您完成了这一切。

这里的目标是使用ADL来定制我们如何漂亮的打印。

传入一个格式化程序标记，并在标记的名称空间中覆盖4个函数(before、after、between和descent)。这改变了在迭代容器时格式化程序打印“装饰品”的方式。

一个默认的格式化程序，它对map执行{(A ->b)，(c->d)}，对tupleoid执行(A,b,c)，对字符串执行"hello"，对包含的所有其他内容执行[x,y,z]。

它应该“只适用于”第三方可迭代类型(并将它们视为“所有其他类型”)。

如果你想为你的第三方可迭代对象定制装饰，只需创建你自己的标签。处理映射下降需要一些工作(您需要重载pretty_print_descent (your_tag返回pretty_print::decorator::map_magic_tag<your_tag>)。也许有更干净的方法，不确定。

一个用于检测可迭代性和元组性的小库:

namespace details {
  using std::begin; using std::end;
  template<class T, class=void>
  struct is_iterable_test:std::false_type{};
  template<class T>
  struct is_iterable_test<T,
    decltype((void)(
      (void)(begin(std::declval<T>())==end(std::declval<T>()))
      , ((void)(std::next(begin(std::declval<T>()))))
      , ((void)(*begin(std::declval<T>())))
      , 1
    ))
  >:std::true_type{};
  template<class T>struct is_tupleoid:std::false_type{};
  template<class...Ts>struct is_tupleoid<std::tuple<Ts...>>:std::true_type{};
  template<class...Ts>struct is_tupleoid<std::pair<Ts...>>:std::true_type{};
  // template<class T, size_t N>struct is_tupleoid<std::array<T,N>>:std::true_type{}; // complete, but problematic
}
template<class T>struct is_iterable:details::is_iterable_test<std::decay_t<T>>{};
template<class T, std::size_t N>struct is_iterable<T(&)[N]>:std::true_type{}; // bypass decay
template<class T>struct is_tupleoid:details::is_tupleoid<std::decay_t<T>>{};

template<class T>struct is_visitable:std::integral_constant<bool, is_iterable<T>{}||is_tupleoid<T>{}> {};

一个允许我们访问iterable或tuple类型对象内容的库:

template<class C, class F>
std::enable_if_t<is_iterable<C>{}> visit_first(C&& c, F&& f) {
  using std::begin; using std::end;
  auto&& b = begin(c);
  auto&& e = end(c);
  if (b==e)
      return;
  std::forward<F>(f)(*b);
}
template<class C, class F>
std::enable_if_t<is_iterable<C>{}> visit_all_but_first(C&& c, F&& f) {
  using std::begin; using std::end;
  auto it = begin(c);
  auto&& e = end(c);
  if (it==e)
      return;
  it = std::next(it);
  for( ; it!=e; it = std::next(it) ) {
    f(*it);
  }
}

namespace details {
  template<class Tup, class F>
  void visit_first( std::index_sequence<>, Tup&&, F&& ) {}
  template<size_t... Is, class Tup, class F>
  void visit_first( std::index_sequence<0,Is...>, Tup&& tup, F&& f ) {
    std::forward<F>(f)( std::get<0>( std::forward<Tup>(tup) ) );
  }
  template<class Tup, class F>
  void visit_all_but_first( std::index_sequence<>, Tup&&, F&& ) {}
  template<size_t... Is,class Tup, class F>
  void visit_all_but_first( std::index_sequence<0,Is...>, Tup&& tup, F&& f ) {
    int unused[] = {0,((void)(
      f( std::get<Is>(std::forward<Tup>(tup)) )
    ),0)...};
    (void)(unused);
  }
}
template<class Tup, class F>
std::enable_if_t<is_tupleoid<Tup>{}> visit_first(Tup&& tup, F&& f) {
  details::visit_first( std::make_index_sequence< std::tuple_size<std::decay_t<Tup>>{} >{}, std::forward<Tup>(tup), std::forward<F>(f) );
}
template<class Tup, class F>
std::enable_if_t<is_tupleoid<Tup>{}> visit_all_but_first(Tup&& tup, F&& f) {
  details::visit_all_but_first( std::make_index_sequence< std::tuple_size<std::decay_t<Tup>>{} >{}, std::forward<Tup>(tup), std::forward<F>(f) );
}

一个漂亮的印刷库:

namespace pretty_print {
  namespace decorator {
    struct default_tag {};
    template<class Old>
    struct map_magic_tag:Old {}; // magic for maps

    // Maps get {}s. Write trait `is_associative` to generalize:
    template<class CharT, class Traits, class...Xs >
    void pretty_print_before( default_tag, std::basic_ostream<CharT, Traits>& s, std::map<Xs...> const& ) {
      s << CharT('{');
    }

    template<class CharT, class Traits, class...Xs >
    void pretty_print_after( default_tag, std::basic_ostream<CharT, Traits>& s, std::map<Xs...> const& ) {
      s << CharT('}');
    }

    // tuples and pairs get ():
    template<class CharT, class Traits, class Tup >
    std::enable_if_t<is_tupleoid<Tup>{}> pretty_print_before( default_tag, std::basic_ostream<CharT, Traits>& s, Tup const& ) {
      s << CharT('(');
    }

    template<class CharT, class Traits, class Tup >
    std::enable_if_t<is_tupleoid<Tup>{}> pretty_print_after( default_tag, std::basic_ostream<CharT, Traits>& s, Tup const& ) {
      s << CharT(')');
    }

    // strings with the same character type get ""s:
    template<class CharT, class Traits, class...Xs >
    void pretty_print_before( default_tag, std::basic_ostream<CharT, Traits>& s, std::basic_string<CharT, Xs...> const& ) {
      s << CharT('"');
    }
    template<class CharT, class Traits, class...Xs >
    void pretty_print_after( default_tag, std::basic_ostream<CharT, Traits>& s, std::basic_string<CharT, Xs...> const& ) {
      s << CharT('"');
    }
    // and pack the characters together:
    template<class CharT, class Traits, class...Xs >
    void pretty_print_between( default_tag, std::basic_ostream<CharT, Traits>&, std::basic_string<CharT, Xs...> const& ) {}

    // map magic. When iterating over the contents of a map, use the map_magic_tag:
    template<class...Xs>
    map_magic_tag<default_tag> pretty_print_descend( default_tag, std::map<Xs...> const& ) {
      return {};
    }
    template<class old_tag, class C>
    old_tag pretty_print_descend( map_magic_tag<old_tag>, C const& ) {
      return {};
    }

    // When printing a pair immediately within a map, use -> as a separator:
    template<class old_tag, class CharT, class Traits, class...Xs >
    void pretty_print_between( map_magic_tag<old_tag>, std::basic_ostream<CharT, Traits>& s, std::pair<Xs...> const& ) {
      s << CharT('-') << CharT('>');
    }
  }

  // default behavior:
  template<class CharT, class Traits, class Tag, class Container >
  void pretty_print_before( Tag const&, std::basic_ostream<CharT, Traits>& s, Container const& ) {
    s << CharT('[');
  }
  template<class CharT, class Traits, class Tag, class Container >
  void pretty_print_after( Tag const&, std::basic_ostream<CharT, Traits>& s, Container const& ) {
    s << CharT(']');
  }
  template<class CharT, class Traits, class Tag, class Container >
  void pretty_print_between( Tag const&, std::basic_ostream<CharT, Traits>& s, Container const& ) {
    s << CharT(',');
  }
  template<class Tag, class Container>
  Tag&& pretty_print_descend( Tag&& tag, Container const& ) {
    return std::forward<Tag>(tag);
  }

  // print things by default by using <<:
  template<class Tag=decorator::default_tag, class Scalar, class CharT, class Traits>
  std::enable_if_t<!is_visitable<Scalar>{}> print( std::basic_ostream<CharT, Traits>& os, Scalar&& scalar, Tag&&=Tag{} ) {
    os << std::forward<Scalar>(scalar);
  }
  // for anything visitable (see above), use the pretty print algorithm:
  template<class Tag=decorator::default_tag, class C, class CharT, class Traits>
  std::enable_if_t<is_visitable<C>{}> print( std::basic_ostream<CharT, Traits>& os, C&& c, Tag&& tag=Tag{} ) {
    pretty_print_before( std::forward<Tag>(tag), os, std::forward<C>(c) );
    visit_first( c, [&](auto&& elem) {
      print( os, std::forward<decltype(elem)>(elem), pretty_print_descend( std::forward<Tag>(tag), std::forward<C>(c) ) );
    });
    visit_all_but_first( c, [&](auto&& elem) {
      pretty_print_between( std::forward<Tag>(tag), os, std::forward<C>(c) );
      print( os, std::forward<decltype(elem)>(elem), pretty_print_descend( std::forward<Tag>(tag), std::forward<C>(c) ) );
    });
    pretty_print_after( std::forward<Tag>(tag), os, std::forward<C>(c) );
  }
}

测试代码:

int main() {
  std::vector<int> x = {1,2,3};

  pretty_print::print( std::cout, x );
  std::cout << "\n";

  std::map< std::string, int > m;
  m["hello"] = 3;
  m["world"] = 42;

  pretty_print::print( std::cout, m );
  std::cout << "\n";
}

生活的例子

这确实使用了c++ 14特性(一些_t别名和auto&& lambdas)，但都不是必需的。

如果boost是一个选项，那么你可以使用boost::algorithm::join。例如，打印std::string的向量:

#include <boost/algorithm/string/join.hpp>

std::vector<std::string> vs { "some", "string", "vector" };
std::cout << boost::algorithm::join(vs, " | ") << '\n';

对于其他类型的向量，首先需要转换为字符串

#include <algorithm>
#include <iostream>
#include <numeric>
#include <vector>

#include <boost/algorithm/string/join.hpp>
#include <boost/range/adaptor/transformed.hpp>

int main()
{
    using boost::adaptors::transformed;
    using boost::algorithm::join;

    // Generate the vector
    std::vector<int> vi(10);
    std::iota(vi.begin(), vi.end(), -3);

    // Print out the vector
    std::cout << join(vi |
                 transformed(static_cast<std::string(*)(int)>(std::to_string)),
                 ", ")
              << '\n';
}

Godbolt演示

我写了一个操作符<<，它输出任何可迭代对象，包括自定义容器、标准容器和具有已知边界的数组。需要c++ 11:

template<typename Container, typename = 
    std::enable_if_t<std::is_same_v<std::void_t<
        decltype(static_cast<typename Container::const_iterator (*)(const Container&)>(&std::cbegin)),
        decltype(static_cast<typename Container::const_iterator (*)(const Container&)>(&std::cend))>, void>
        && !std::is_same_v<std::string, Container>>>
std::ostream& operator<<(std::ostream& out, const Container &vec)
{
    std::cout << "[ ";
    for(const auto& t: vec){
        std::cout << t << " ";
    }
    std::cout << "] ";
    return out;
}

模板收集:

应用std::cout <<和std::to_string

std::vector、std::array和std::tuple

由于在cpp中打印一个向量被证明是惊人的工作量(至少与这个任务的基本程度相比)，并且作为再次跨越相同问题的一个步骤，当使用其他容器时，这里有一个更通用的解决方案…

模板收集内容

这个模板集合处理3种容器类型: Std::vector, Std::array和Std::tuple。 它为这些对象定义了std::to_string()，并可以通过std::cout << container;直接将它们打印出来。

此外，它还为std::string << container定义了<<运算符。 这样就可以以紧凑的方式构造包含这些容器类型的字符串。

From

std::string s1 = "s1: " + std::to_string(arr) + "; " + std::to_string(vec) + "; " + std::to_string(tup);

我们会讲到

std::string s2 = STR() << "s2: " << arr << "; " << vec << "; " << tup;

Code

您可以交互地测试这段代码:这里。

#include <iostream>
#include <string>
#include <tuple>
#include <vector>
#include <array>

namespace std
{   
    // declations: needed for std::to_string(std::vector<std::tuple<int, float>>)
    std::string to_string(std::string str);
    std::string to_string(const char *str);
    template<typename T, size_t N>
    std::string to_string(std::array<T, N> const& arr);
    template<typename T>
    std::string to_string(std::vector<T> const& vec);
    template<typename... Args>
    std::string to_string(const std::tuple<Args...>& tup);
    
    std::string to_string(std::string str)
    {
        return std::string(str);
    }
    std::string to_string(const char *str)
    {
        return std::string(str);
    }

    template<typename T, size_t N>
    std::string to_string(std::array<T, N> const& arr)
    {
        std::string s="{";
        for (std::size_t t = 0; t != N; ++t)
            s += std::to_string(arr[t]) + (t+1 < N ? ", ":"");
        return s + "}";
    }

    template<typename T>
    std::string to_string(std::vector<T> const& vec)
    {
        std::string s="[";
        for (std::size_t t = 0; t != vec.size(); ++t)
            s += std::to_string(vec[t]) + (t+1 < vec.size() ? ", ":"");
        return s + "]";
    }
    
    // to_string(tuple)
    // https://en.cppreference.com/w/cpp/utility/tuple/operator%3D
    template<class Tuple, std::size_t N>
    struct TupleString
    {
        static std::string str(const Tuple& tup)
        {
            std::string out;
            out += TupleString<Tuple, N-1>::str(tup);
            out += ", ";
            out += std::to_string(std::get<N-1>(tup));
            return out;
        }
    };
    template<class Tuple>
    struct TupleString<Tuple, 1>
    {
        static std::string str(const Tuple& tup)
        {
            std::string out;
            out += std::to_string(std::get<0>(tup));
            return out;
        }
    };
    template<typename... Args>
    std::string to_string(const std::tuple<Args...>& tup)
    {
        std::string out = "(";
        out += TupleString<decltype(tup), sizeof...(Args)>::str(tup);
        out += ")";
        return out;
    }
} // namespace std


/**
 * cout: cout << continer
 */
template <typename T, std::size_t N> // cout << array
std::ostream& operator <<(std::ostream &out, std::array<T, N> &con)
{
    out <<  std::to_string(con);
    return out;
}
template <typename T, typename A> // cout << vector
std::ostream& operator <<(std::ostream &out, std::vector<T, A> &con)
{
    out <<  std::to_string(con);
    return out;
}
template<typename... Args> // cout << tuple
std::ostream& operator <<(std::ostream &out, std::tuple<Args...> &con)
{
    out <<  std::to_string(con);
    return out;
}

/**
 * Concatenate: string << continer
 */
template <class C>
std::string operator <<(std::string str, C &con)
{
    std::string out = str;
    out += std::to_string(con);
    return out;
}
#define STR() std::string("")

int main()
{
    std::array<int, 3> arr {1, 2, 3};
    std::string sArr = std::to_string(arr);
    std::cout << "std::array" << std::endl;
    std::cout << "\ttest to_string: " << sArr << std::endl;
    std::cout << "\ttest cout <<: " << arr << std::endl;
    std::cout << "\ttest string <<: " << (std::string() << arr) << std::endl;
    
    std::vector<std::string> vec {"a", "b"};
    std::string sVec = std::to_string(vec);
    std::cout << "std::vector" << std::endl;
    std::cout << "\ttest to_string: " << sVec << std::endl;
    std::cout << "\ttest cout <<: " << vec << std::endl;
    std::cout << "\ttest string <<: " << (std::string() << vec) << std::endl;
    
    std::tuple<int, std::string> tup = std::make_tuple(5, "five");
    std::string sTup = std::to_string(tup);
    std::cout << "std::tuple" << std::endl;
    std::cout << "\ttest to_string: " << sTup << std::endl;
    std::cout << "\ttest cout <<: " << tup << std::endl;
    std::cout << "\ttest string <<: " << (std::string() << tup) << std::endl;
    
    std::vector<std::tuple<int, float>> vt {std::make_tuple(1, .1), std::make_tuple(2, .2)};
    std::string sVt = std::to_string(vt);
    std::cout << "std::vector<std::tuple>" << std::endl;
    std::cout << "\ttest to_string: " << sVt << std::endl;
    std::cout << "\ttest cout <<: " << vt << std::endl;
    std::cout << "\ttest string <<: " << (std::string() << vt) << std::endl;
    
    std::cout << std::endl;
    
    std::string s1 = "s1: " + std::to_string(arr) + "; " + std::to_string(vec) + "; " + std::to_string(tup);
    std::cout << s1 << std::endl;
    
    std::string s2 = STR() << "s2: " << arr << "; " << vec << "; " << tup;
    std::cout << s2 << std::endl;

    return 0;
}

输出

std::array
    test to_string: {1, 2, 3}
    test cout <<: {1, 2, 3}
    test string <<: {1, 2, 3}
std::vector
    test to_string: [a, b]
    test cout <<: [a, b]
    test string <<: [a, b]
std::tuple
    test to_string: (5, five)
    test cout <<: (5, five)
    test string <<: (5, five)
std::vector<std::tuple>
    test to_string: [(1, 0.100000), (2, 0.200000)]
    test cout <<: [(1, 0.100000), (2, 0.200000)]
    test string <<: [(1, 0.100000), (2, 0.200000)]

s1: {1, 2, 3}; [a, b]; (5, five)
s2: {1, 2, 3}; [a, b]; (5, five)

这个解决方案的灵感来自Marcelo的解决方案，有一些变化:

#include <iostream>
#include <iterator>
#include <type_traits>
#include <vector>
#include <algorithm>

// This works similar to ostream_iterator, but doesn't print a delimiter after the final item
template<typename T, typename TChar = char, typename TCharTraits = std::char_traits<TChar> >
class pretty_ostream_iterator : public std::iterator<std::output_iterator_tag, void, void, void, void>
{
public:
    typedef TChar char_type;
    typedef TCharTraits traits_type;
    typedef std::basic_ostream<TChar, TCharTraits> ostream_type;

    pretty_ostream_iterator(ostream_type &stream, const char_type *delim = NULL)
        : _stream(&stream), _delim(delim), _insertDelim(false)
    {
    }

    pretty_ostream_iterator<T, TChar, TCharTraits>& operator=(const T &value)
    {
        if( _delim != NULL )
        {
            // Don't insert a delimiter if this is the first time the function is called
            if( _insertDelim )
                (*_stream) << _delim;
            else
                _insertDelim = true;
        }
        (*_stream) << value;
        return *this;
    }

    pretty_ostream_iterator<T, TChar, TCharTraits>& operator*()
    {
        return *this;
    }

    pretty_ostream_iterator<T, TChar, TCharTraits>& operator++()
    {
        return *this;
    }

    pretty_ostream_iterator<T, TChar, TCharTraits>& operator++(int)
    {
        return *this;
    }
private:
    ostream_type *_stream;
    const char_type *_delim;
    bool _insertDelim;
};

#if _MSC_VER >= 1400

// Declare pretty_ostream_iterator as checked
template<typename T, typename TChar, typename TCharTraits>
struct std::_Is_checked_helper<pretty_ostream_iterator<T, TChar, TCharTraits> > : public std::tr1::true_type
{
};

#endif // _MSC_VER >= 1400

namespace std
{
    // Pre-declarations of container types so we don't actually have to include the relevant headers if not needed, speeding up compilation time.
    // These aren't necessary if you do actually include the headers.
    template<typename T, typename TAllocator> class vector;
    template<typename T, typename TAllocator> class list;
    template<typename T, typename TTraits, typename TAllocator> class set;
    template<typename TKey, typename TValue, typename TTraits, typename TAllocator> class map;
}

// Basic is_container template; specialize to derive from std::true_type for all desired container types
template<typename T> struct is_container : public std::false_type { };

// Mark vector as a container
template<typename T, typename TAllocator> struct is_container<std::vector<T, TAllocator> > : public std::true_type { };

// Mark list as a container
template<typename T, typename TAllocator> struct is_container<std::list<T, TAllocator> > : public std::true_type { };

// Mark set as a container
template<typename T, typename TTraits, typename TAllocator> struct is_container<std::set<T, TTraits, TAllocator> > : public std::true_type { };

// Mark map as a container
template<typename TKey, typename TValue, typename TTraits, typename TAllocator> struct is_container<std::map<TKey, TValue, TTraits, TAllocator> > : public std::true_type { };

// Holds the delimiter values for a specific character type
template<typename TChar>
struct delimiters_values
{
    typedef TChar char_type;
    const TChar *prefix;
    const TChar *delimiter;
    const TChar *postfix;
};

// Defines the delimiter values for a specific container and character type
template<typename T, typename TChar>
struct delimiters
{
    static const delimiters_values<TChar> values; 
};

// Default delimiters
template<typename T> struct delimiters<T, char> { static const delimiters_values<char> values; };
template<typename T> const delimiters_values<char> delimiters<T, char>::values = { "{ ", ", ", " }" };
template<typename T> struct delimiters<T, wchar_t> { static const delimiters_values<wchar_t> values; };
template<typename T> const delimiters_values<wchar_t> delimiters<T, wchar_t>::values = { L"{ ", L", ", L" }" };

// Delimiters for set
template<typename T, typename TTraits, typename TAllocator> struct delimiters<std::set<T, TTraits, TAllocator>, char> { static const delimiters_values<char> values; };
template<typename T, typename TTraits, typename TAllocator> const delimiters_values<char> delimiters<std::set<T, TTraits, TAllocator>, char>::values = { "[ ", ", ", " ]" };
template<typename T, typename TTraits, typename TAllocator> struct delimiters<std::set<T, TTraits, TAllocator>, wchar_t> { static const delimiters_values<wchar_t> values; };
template<typename T, typename TTraits, typename TAllocator> const delimiters_values<wchar_t> delimiters<std::set<T, TTraits, TAllocator>, wchar_t>::values = { L"[ ", L", ", L" ]" };

// Delimiters for pair
template<typename T1, typename T2> struct delimiters<std::pair<T1, T2>, char> { static const delimiters_values<char> values; };
template<typename T1, typename T2> const delimiters_values<char> delimiters<std::pair<T1, T2>, char>::values = { "(", ", ", ")" };
template<typename T1, typename T2> struct delimiters<std::pair<T1, T2>, wchar_t> { static const delimiters_values<wchar_t> values; };
template<typename T1, typename T2> const delimiters_values<wchar_t> delimiters<std::pair<T1, T2>, wchar_t>::values = { L"(", L", ", L")" };

// Functor to print containers. You can use this directly if you want to specificy a non-default delimiters type.
template<typename T, typename TChar = char, typename TCharTraits = std::char_traits<TChar>, typename TDelimiters = delimiters<T, TChar> >
struct print_container_helper
{
    typedef TChar char_type;
    typedef TDelimiters delimiters_type;
    typedef std::basic_ostream<TChar, TCharTraits>& ostream_type;

    print_container_helper(const T &container)
        : _container(&container)
    {
    }

    void operator()(ostream_type &stream) const
    {
        if( delimiters_type::values.prefix != NULL )
            stream << delimiters_type::values.prefix;
        std::copy(_container->begin(), _container->end(), pretty_ostream_iterator<typename T::value_type, TChar, TCharTraits>(stream, delimiters_type::values.delimiter));
        if( delimiters_type::values.postfix != NULL )
            stream << delimiters_type::values.postfix;
    }
private:
    const T *_container;
};

// Prints a print_container_helper to the specified stream.
template<typename T, typename TChar, typename TCharTraits, typename TDelimiters>
std::basic_ostream<TChar, TCharTraits>& operator<<(std::basic_ostream<TChar, TCharTraits> &stream, const print_container_helper<T, TChar, TDelimiters> &helper)
{
    helper(stream);
    return stream;
}

// Prints a container to the stream using default delimiters
template<typename T, typename TChar, typename TCharTraits>
typename std::enable_if<is_container<T>::value, std::basic_ostream<TChar, TCharTraits>&>::type
    operator<<(std::basic_ostream<TChar, TCharTraits> &stream, const T &container)
{
    stream << print_container_helper<T, TChar, TCharTraits>(container);
    return stream;
}

// Prints a pair to the stream using delimiters from delimiters<std::pair<T1, T2>>.
template<typename T1, typename T2, typename TChar, typename TCharTraits>
std::basic_ostream<TChar, TCharTraits>& operator<<(std::basic_ostream<TChar, TCharTraits> &stream, const std::pair<T1, T2> &value)
{
    if( delimiters<std::pair<T1, T2>, TChar>::values.prefix != NULL )
        stream << delimiters<std::pair<T1, T2>, TChar>::values.prefix;

    stream << value.first;

    if( delimiters<std::pair<T1, T2>, TChar>::values.delimiter != NULL )
        stream << delimiters<std::pair<T1, T2>, TChar>::values.delimiter;

    stream << value.second;

    if( delimiters<std::pair<T1, T2>, TChar>::values.postfix != NULL )
        stream << delimiters<std::pair<T1, T2>, TChar>::values.postfix;
    return stream;    
}

// Used by the sample below to generate some values
struct fibonacci
{
    fibonacci() : f1(0), f2(1) { }
    int operator()()
    {
        int r = f1 + f2;
        f1 = f2;
        f2 = r;
        return f1;
    }
private:
    int f1;
    int f2;
};

int main()
{
    std::vector<int> v;
    std::generate_n(std::back_inserter(v), 10, fibonacci());

    std::cout << v << std::endl;

    // Example of using pretty_ostream_iterator directly
    std::generate_n(pretty_ostream_iterator<int>(std::cout, ";"), 20, fibonacci());
    std::cout << std::endl;
}

与Marcelo的版本一样，它使用了一个is_container类型的特征，必须为所有要支持的容器特殊化。也许可以使用trait来检查value_type、const_iterator、begin()/end()，但我不确定我是否会推荐这样做，因为它可能匹配那些符合这些标准但实际上不是容器的东西，比如std::basic_string。同样像Marcelo的版本一样，它使用可以专门化的模板来指定要使用的分隔符。

主要的区别是，我围绕pretty_ostream_iterator构建了我的版本，它的工作原理类似于std::ostream_iterator，但没有在最后一项后面打印分隔符。容器的格式化是由print_container_helper完成的，它可以直接用于打印不带is_container特征的容器，或指定不同的分隔符类型。

我还定义了is_container和分隔符，因此它将适用于具有非标准谓词或分配器的容器，以及char和wchar_t。操作符<<函数本身也被定义为同时使用char和wchar_t流。

最后，我使用了std::enable_if，它是c++0x的一部分，在Visual c++ 2010和g++ 4.3(需要-std=c++0x标志)和更高版本中可用。这样就不依赖于Boost。