可以boost：algorithm :: join（）concat一个容器的浮点数？ [英] Can boost:algorithm::join() concat a container of floats?

问题描述

Boost连接可用于连接可选用分隔符字符串分隔的字符串容器。在此stackovwerflow示例中： boost :: algorithm :: join 的一个很好的示例

我的STL技能很弱。我想知道是否还有使用相同的函数为一个数字的容器（浮点数，双精度，整数）？

还有一个stl的复制函数，有一个很好的例子：
C ++打印出向量的内容

但我不喜欢如何在每个元素后面添加分隔符字符串。我想只使用boost。

感谢。

解决方案

当然，您可以结合 boost :: algorithm :: join 和 boost :: adapters :: transformed 将双精度转换为字符串，然后将它们连接在一起。 / p>

  #include< iostream& 
 #include< vector> 
 #include< string> 
 
 #include< boost / algorithm / string / join.hpp> 
 #include< boost / range / adapter / transformed.hpp> 
 
 int main（）
 {
使用boost :: adapters :: transformed; 
 using boost :: algorithm :: join; 
 
 std :: vector< double> v {1.1，2.2，3.3，4.4}; 
 
 std :: cout 
<< join（v | 
 transformed（static_cast< std :: string（*）（double）>（std :: to_string）），
，）; 
} 
  

输出：

< >

1.100000，2.200000，3.300000，4.400000

Boost join can be used to concatenate a container of strings optionally separated by a separator string. In this stackovwerflow example: A good example for boost::algorithm::join

My STL skills are weak. I'm wondering if there is anyway to use the same function for a container of numbers (floats, doubles, ints)? It just seems like there should some one- or two-liner to adapt it for other types.

There is also stl's copy function with a good example found here: C++ Printing out the contents of a vector

But I don't like how it adds the separator string after every element. I'd like to just use boost.

thanks.

解决方案

Sure, you can combine boost::algorithm::join and boost::adaptors::transformed to convert the doubles to strings and then join them together.

#include <iostream>
#include <vector>
#include <string>

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

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

    std::vector<double> v{1.1, 2.2, 3.3, 4.4};

    std::cout 
      << join( v | 
               transformed( static_cast<std::string(*)(double)>(std::to_string) ), 
               ", " );
}

Output:

1.100000, 2.200000, 3.300000, 4.400000

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