std::between() an idea by Niels Dekker

gistfile1.txt

// std::between() an idea by Niels Dekker

#include <functional>

namespace std {

template<class T>
bool between(T const& val, T const& lo, T const& hi)
{
    return between( val, lo, hi, std::less<T>() );
}

template<class T, class Compare>
bool between(T const& val, T const& lo, T const& hi, Compare comp)
{
    return comp(lo, val) && comp(val, hi);
}

}

#include <cassert>
#include <cstdlib>
#include <limits>

int main()
{
    assert(   std::between( rand(), 0, RAND_MAX ) );

    assert( ! std::between( 2, 3, 7 ) );
    assert( ! std::between( 3, 3, 7 ) );
    assert(   std::between( 4, 3, 7 ) );
    assert(   std::between( 5, 3, 7 ) );
    assert(   std::between( 6, 3, 7 ) );
    assert( ! std::between( 7, 3, 7 ) );
    assert( ! std::between( 8, 3, 7 ) );

    assert( ! std::between( 2.0, 3.0, 7.0 ) );
    assert( ! std::between( 3.0, 3.0, 7.0 ) );
    assert(   std::between( 4.0, 3.0, 7.0 ) );
    assert(   std::between( 5.0, 3.0, 7.0 ) );
    assert(   std::between( 6.0, 3.0, 7.0 ) );
    assert( ! std::between( 7.0, 3.0, 7.0 ) );
    assert( ! std::between( 8.0, 3.0, 7.0 ) );

    assert( ! std::between( 1.0 - std::numeric_limits<double>::epsilon(), 1.0, 7.0 ) );
    assert( ! std::between( 1.0                                         , 1.0, 7.0 ) );
    assert(   std::between( 1.0 + std::numeric_limits<double>::epsilon(), 1.0, 7.0 ) );
}

// cl -nologo -EHsc between.cpp && between
// g++ -Wall -Wextra -Weffc++ -std=c++11 -o between.exe between.cpp && between

On 25-Apr-21 21:18, Oliver Smith wrote: ***@***.**** commented on this gist. ------------------------------------------------------------------------------- If you make the default for comp be std::less_equal you could consolidate to a single implementation? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <https://gist.github.com/9410391#gistcomment-3719424>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAPIDOT2SPYHZVBPJFEJNZ3TKRTJ3ANCNFSM43RSSICQ>.

Indeed, that's possible for C++14 and later, but not for C++11. template<class T, class Compare = std::less_equal<> > bool between(T const& val, T const& lo, T const& hi, Compare comp = Compare{} ) { return comp(lo, val) && comp(val, hi); }