count_if

count_if_t kumi::count_if {}

inlineconstexprnoexcept

Callable object counting the number of elements of t satisfying predicates p.

On a record type, the function operates on the underlying elements of the fields.

Header file

#include <kumi/algorithm/predicates.hpp>

Call Signature

template<product_type T, typename Pred>
constexpr auto count_if(T && t, Pred p) noexcept;

Parameters

• t: Product Type to process
• p: Unary predicate

Return value

• Number of elements satisfying the condition.

Examples

• Tuple

  
  #include <kumi/kumi.hpp>
  #include <iostream>
  #include <type_traits>
   
  int main()
  {
    auto t = kumi::tuple{1, 2., 3.f, 'z'};
    std::cout << std::boolalpha
              << kumi::count_if( t, kumi::predicate<std::is_floating_point>() ) << "\n";
  }

• Record

  
  #include <kumi/kumi.hpp>
  #include <iostream>
  #include <type_traits>
   
  int main()
  {
    using namespace kumi::literals;
    auto r = kumi::record{"a"_id = 1, "b"_id = 2.,"c"_id =  3.f, "d"_id = 'z'};
    std::cout << std::boolalpha
              << kumi::count_if( r, kumi::predicate<std::is_floating_point>() ) << "\n";
  }