count_if()

template<typename Pred, concepts::product_type T>

std::size_t kumi::count_if ( T && t, Pred p )

inlinenodiscardconstexprnoexcept

Counts the number of elements of t satisfying predicates p.

Parameters

t	Product Type to process
p	Unary predicate. p must return a value convertible to bool for every element of t.

Returns

Number of elements satisfying the condition.

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

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";
}