Can boost:algorithm::join() concat a container of floats?

Question

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

Answer 1

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

#include 
#include 
#include 

#include 
#include 

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

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

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

Output:

1.100000, 2.200000, 3.300000, 4.400000

---

You can also use a lambda to avoid the ugly cast

join(v | transformed([](double d) { return std::to_string(d); }), ", ")