C ++ cout自动分隔符 [英] C++ cout auto separator

问题描述

我想知道 std :: cout 是否会自动在打印的序列之间插入一些预定义的值。

例如：

  std :: cout< 2<< 3<< 33<< 45 < std :: endl; 
  

输出

  233345 
  

，我想输出

  2 3 33 45 
  

知道，很容易：

  std :: cout< 2<< < 3<< < 33<< < 45 < std :: endl; 
  

但我想知道是否有自动化的方法，例如：

  std :: cout< set_some_separator（）< 2<< 3<< 33<< 45 < std :: endl;任何人都知道这样的东西是可能的？
 
 

=

h2_lin>解决方案

好吧，我受到了打击。

编辑：好，在阅读Nim的回答后，我的 p>

  #include< iostream> 
 #include< algorithm> 
 
 struct with_separator {
 with_separator（std :: string sep）
：sep（std :: move（sep））{} 
 
 std： ：string sep; 
}; 
 
 struct separated_stream {
 separated_stream（std :: ostream& stream，std :: string sep）
：_stream（stream），_sep（std :: move ），_first（true）{} 
 
 template< class Rhs> 
 separated_stream& operator<< （Rhs&& rhs）{
 if（_first）
 _first = false; 
 else 
 _stream<< _sep; 
 
 _stream<< std :: forward< Rhs>（rhs）; 
 return * this; 
} 
 
 separated_stream& operator<< （std :: ostream&（* manip）（std :: ostream&））{
 manip（_stream）; 
 return * this; 
} 
 
 private：
 std :: ostream& _stream; 
 std :: string _sep; 
 bool _first; 
}; 
 
 separated_stream operator<< （std :: ostream& stream，with_separator wsep）{
 return separated_stream（stream，std :: move（wsep.sep））; 
} 
 
 int main（）
 {
 std :: cout< with_separator（，）<< 1<< 2<< 3<< std :: endl; 
} 
  

输出：

  1，2，3 
  

I am wondering if there is way that std::cout automatically will insert some predefined value between printed sequences.

For example:

std::cout << 2 << 3 << 33 << 45 << std::endl;

outputs

233345

and I would like it to output

2 3 33 45

and I know, that it's easy to:

std::cout << 2 << " " << 3 <<  " " << 33 <<  " " << 45 << std::endl;

But I'am wondering if there is a way to automate this, such as:

std::cout << set_some_separator(" ") << 2 << 3 << 33 << 45 << std::endl;

Anyone aware of something like this being possible?

解决方案

Well, I got beaten to it. I'll post this anyway.

Edit : well, after reading Nim's answer, mine does achieve the exact syntax OP wished for.

#include <iostream>
#include <algorithm>

struct with_separator {
    with_separator(std::string sep)
    : sep(std::move(sep)) {}

    std::string sep;
};

struct separated_stream {
    separated_stream(std::ostream &stream, std::string sep)
    : _stream(stream), _sep(std::move(sep)), _first(true) {}

    template <class Rhs>
    separated_stream &operator << (Rhs &&rhs) {
        if(_first)
            _first = false;
        else
            _stream << _sep;

        _stream << std::forward<Rhs>(rhs);
        return *this;
    }

    separated_stream &operator << (std::ostream &(*manip)(std::ostream&)) {
        manip(_stream);
        return *this;
    }

    private:
    std::ostream &_stream;
    std::string _sep;
    bool _first;
};

separated_stream operator << (std::ostream &stream, with_separator wsep) {
    return separated_stream(stream, std::move(wsep.sep));
}

int main()
{
    std::cout << with_separator(", ") << 1 << 2 << 3 << std::endl;
}

Output :

1, 2, 3

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