What is the source code for a method called max?

Answer 1

That depends on the programming language and the exact implementation of max. Normally, a max function returns the largest of two variables of the same type but can also be applied to a sequence container with 2 or more elements. Both versions may also include a user-defined predicate to perform the comparison(s).

In the C++ standard library, it is implemented as a generic algorithm (a function template) with 4 overloads. These functions become accessible when you include the <algorithm> header from the standard library. They each have the following definitions:

// TEMPLATE FUNCTION max

template<class _Ty> inline

_Post_equal_to_(_Left < _Right ? _Right : _Left)

const _Ty& (max)(const _Ty& _Left, const _Ty& _Right)

{ // return larger of _Left and _Right

return (_DEBUG_LT(_Left, _Right) ? _Right : _Left);

}

template<class _Ty> inline

_Ty (max)(_XSTD initializer_list<_Ty> _Ilist)

{ // return leftmost/largest

const _Ty *_Res = _STD max_element(_Ilist.begin(), _Ilist.end());

return (*_Res);

}

// TEMPLATE FUNCTION max WITH PRED

template<class _Ty,

class _Pr> inline

const _Ty& (max)(const _Ty& _Left, const _Ty& _Right, _Pr _Pred)

{ // return larger of _Left and _Right using _Pred

return (_DEBUG_LT_PRED(_Pred, _Left, _Right) ? _Right : _Left);

}

template<class _Ty,

class _Pr> inline

_Ty (max)(_XSTD initializer_list<_Ty> _Ilist, _Pr _Pred)

{ // return leftmost/largest

const _Ty *_Res = _STD max_element(_Ilist.begin(), _Ilist.end(), _Pred);

return (*_Res);

}