From cppreference.com
Defined in header
Call signature
template<classT,classProj=std::identity,std::indirect_strict_weak_order<std::projected<constT*,Proj>>Comp=ranges::less>constexprconstT&min(constT&a,constT&b,Compcomp={},Projproj={}); (1) (since C++20)template<std::copyableT,classProj=std::identity,std::indirect_strict_weak_order<std::projected<constT*,Proj>>Comp=ranges::less>constexprTmin(std::initializer_list<T>r,Compcomp={},Projproj={}); (2) (since C++20)template<ranges::input_rangeR,classProj=std::identity,std::indirect_strict_weak_order<std::projected<ranges::iterator_t<R>,Proj>>Comp=ranges::less>requiresstd::indirectly_copyable_storable<ranges::iterator_t<R>,ranges::range_value_t<R>*>constexprranges::range_value_t<R>min(R&&r,Compcomp={},Projproj={}); (3) (since C++20)Returns the smaller of the given projected elements.
1) Returns the smaller of a and b.
2) Returns the first smallest element in the initializer list r.
3) Returns the first smallest value in the range r.
The function-like entities described on this page are
(informally known as niebloids), that is:
Explicit template argument lists cannot be specified when calling any of them.
None of them are visible to
.
When any of them are found by
as the name to the left of the function-call operator,
is inhibited.
Parameters
a, b - the values to compare r - the range of values to compare comp - comparison to apply to the projected elements proj - projection to apply to the elements Return value
1) The smaller of a and b, according to the projection. If they are equivalent, returns a.
2,3) The smallest element in r, according to the projection. If several values are equivalent to the smallest, returns the leftmost one. If the range is empty (as determined by ranges::distance(r)), the behavior is undefined.
Complexity
1) Exactly one comparison.
2,3) Exactly ranges::distance(r)-1 comparisons.
Possible implementation
structmin_fn{template<classT,classProj=std::identity,std::indirect_strict_weak_order<std::projected<constT*,Proj>>Comp=ranges::less>constexprconstT&operator()(constT&a,constT&b,Compcomp={},Projproj={})const{returnstd::invoke(comp,std::invoke(proj,b),std::invoke(proj,a))?b:a;}template<std::copyableT,classProj=std::identity,std::indirect_strict_weak_order<std::projected<constT*,Proj>>Comp=ranges::less>constexprToperator()(std::initializer_list<T>r,Compcomp={},Projproj={})const{return*ranges::min_element(r,std::ref(comp),std::ref(proj));}template<ranges::input_rangeR,classProj=std::identity,std::indirect_strict_weak_order<std::projected<ranges::iterator_t<R>,Proj>>Comp=ranges::less>requiresstd::indirectly_copyable_storable<ranges::iterator_t<R>,ranges::range_value_t<R>*>constexprranges::range_value_t<R>operator()(R&&r,Compcomp={},Projproj={})const{usingV=ranges::range_value_t<R>;ifconstexpr(ranges::forward_range<R>)returnstatic_cast<V>(*ranges::min_element(r,std::ref(comp),std::ref(proj)));else{autoi=ranges::begin(r);autos=ranges::end(r);Vm(*i);while(++i!=s)if(std::invoke(comp,std::invoke(proj,*i),std::invoke(proj,m)))m=*i;returnm;}}};inlineconstexprmin_fnmin;Notes
Capturing the result of std::ranges::min by reference produces a dangling reference if one of the parameters is a temporary and that parameter is returned:
intn=-1;constint&r=std::ranges::min(n+2,n*2);// r is danglingExample
Run this code
#include<algorithm>#include<iostream>#include<string>intmain(){namespaceranges=std::ranges;usingnamespacestd::string_view_literals;std::cout<<"smaller of 1 and 9999: "<<ranges::min(1,9999)<<'\n'<<"smaller of 'a', and 'b': '"<<ranges::min('a','b')<<"'\n"<<"shortest of \"foo\", \"bar\", and \"hello\": \""<<ranges::min({"foo"sv,"bar"sv,"hello"sv},{},&std::string_view::size)<<"\"\n";}Output:
smaller of 1 and 9999: 1 smaller of 'a', and 'b': 'a' shortest of "foo", "bar", and "hello": "foo" See also
(C++20)
returns the greater of the given values
(algorithm function object)
(C++20)
returns the smaller and larger of two elements
(algorithm function object)
(C++20)
returns the smallest element in a range
(algorithm function object)
(C++20)
clamps a value between a pair of boundary values
(algorithm function object)
returns the smaller of the given values
(function template)