std::minmax

 

C++

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Regular expressions library (C++11)

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Technical Specifications

 

Algorithm library

Functions
Non-modifying sequence operations
all_ofany_ofnone_of (C++11)(C++11)(C++11) for_each countcount_if mismatch equal	findfind_iffind_if_not (C++11) find_end find_first_of adjacent_find search search_n
Modifying sequence operations
copycopy_if (C++11) copy_n (C++11) copy_backward move (C++11) move_backward (C++11) fill fill_n transform generate generate_n removeremove_if remove_copyremove_copy_if	replacereplace_if replace_copyreplace_copy_if swap swap_ranges iter_swap reverse reverse_copy rotate rotate_copy random_shuffleshuffle (until C++17)(C++11) unique unique_copy
Partitioning operations
is_partitioned (C++11) partition partition_copy (C++11)	stable_partition partition_point (C++11)
Sorting operations (on sorted ranges)
is_sorted (C++11) is_sorted_until (C++11) sort	partial_sort partial_sort_copy stable_sort nth_element
Binary search operations (on sorted ranges)
lower_bound upper_bound	binary_search equal_range
Set operations (on sorted ranges)
merge inplace_merge includes	set_difference set_intersection set_symmetric_difference set_union
Heap operations
is_heap (C++11) is_heap_until (C++11) make_heap	push_heap pop_heap sort_heap
Minimum/maximum operations
max max_element min min_element minmax (C++11) minmax_element (C++11)	lexicographical_compare is_permutation (C++11) next_permutation prev_permutation
Numeric operations
iota (C++11) accumulate inner_product	adjacent_difference partial_sum
C library
qsort	bsearch

 

Defined in header <algorithm>
	(1)
template< class T > std::pair<const T&,const T&> minmax( const T& a, const T& b );			(since C++11) (until C++14)
template< class T > constexpr std::pair<const T&,const T&> minmax( const T& a, const T& b );			(since C++14)
		(2)
template< class T, class Compare > std::pair<const T&,const T&> minmax( const T& a, const T& b,                                      Compare comp );				(since C++11) (until C++14)
template< class T, class Compare > constexpr std::pair<const T&,const T&> minmax( const T& a, const T& b,                                                Compare comp );				(since C++14)
			(3)
template< class T > std::pair<T,T> minmax( std::initializer_list<T> ilist);					(since C++11) (until C++14)
template< class T > constexpr std::pair<T,T> minmax( std::initializer_list<T> ilist);					(since C++14)
				(4)
template< class T, class Compare > std::pair<T,T> minmax( std::initializer_list<T> ilist, Compare comp );						(since C++11) (until C++14)
template< class T, class Compare > constexpr std::pair<T,T> minmax( std::initializer_list<T> ilist, Compare comp );						(since C++14)

Returns the lowest and the greatest of the given values.

1-2) Returns references to the smaller and the greater of a and b.

3-4) Returns the smallest and the greatest of the values in initializer list ilist.

The (1,3) versions use operator< to compare the values, whereas the (2,4) versions use the given comparison function comp.

Parameters

a, b	-	the values to compare
ilist	-	initializer list with the values to compare
comp	-	comparison function object (i.e. an object that satisfies the requirements of Compare) which returns ​true if the first argument is less than the second. The signature of the comparison function should be equivalent to the following:  bool cmp(const Type1 &a, const Type2 &b); The signature does not need to have const &, but the function object must not modify the objects passed to it. The types Type1 and Type2 must be such that an object of type T can be implicitly converted to both of them. ​
Type requirements
- T must meet the requirements of LessThanComparable in order to use overloads (1,3).
- T must meet the requirements of CopyConstructible in order to use overloads (3,4).

Return value

1-2) Returns the result of std::pair<const T&, const T&>(a, b) if a<b or if a is equivalent to b. Returns the result of std::pair<const T&, const T&>(b, a) if b<a.

3-4) A pair with the smallest value in ilist as the first element and the greatest as the second. If several elements are equivalent to the smallest, the leftmost such element is returned. If several elements are equivalent to the largest, the rightmost such element is returned.

Complexity

1-2) Exactly one comparison

3-4) At most ilist.size() * 3 / 2 comparisons

Possible implementation

First version
template<class T> std::pair<const T&, const T&> minmax( const T& a, const T& b ) { return (b < a) ? std::pair<const T&, const T&>(b, a) : std::pair<const T&, const T&>(a, b); }
Second version
template<class T, class Compare> std::pair<const T&, const T&> minmax( const T& a, const T& b, Compare comp ) { return comp(b, a) ? std::pair<const T&, const T&>(b, a) : std::pair<const T&, const T&>(a, b); }
Third version
template< class T > std::pair<T, T> minmax( std::initializer_list<T> ilist ) { auto p = std::minmax_element(ilist.begin(), ilist.end()); return std::make_pair(*p.first, *p.second); }
Fourth version
template< class T, class Compare > std::pair<T, T> minmax( std::initializer_list<T> ilist, Compare comp ) { auto p = std::minmax_element(ilist.begin(), ilist.end(), comp); return std::make_pair(*p.first, *p.second); }

Notes

For overloads (1,2), if one of the parameters is an rvalue, the reference returned becomes a dangling reference at the end of the full expression that contains the call to minmax:

int n = 1;
auto p = std::minmax(n, n+1);
int m = p.first; // ok
int x = p.second; // undefined behavior

Example

Run this code

#include <algorithm>
#include <iostream>
#include <vector>
#include <cstdlib>
#include <ctime>
 
int main()
{
    std::vector<int> v {3, 1, 4, 1, 5, 9, 2, 6}; 
    std::srand(std::time(0));
    std::pair<int, int> bounds = std::minmax(std::rand() % v.size(),
                                             std::rand() % v.size());
 
    std::cout << "v[" << bounds.first << "," << bounds.second << "]: ";
    for (int i = bounds.first; i < bounds.second; ++i) {
        std::cout << v[i] << ' ';
    }
    std::cout << '\n';
}

Possible output:

v[2,7]: 4 1 5 9 2

See also

min	returns the smaller of the given values (function template)
max	returns the greater of the given values (function template)
minmax_element (C++11)	returns the smallest and the largest element in a range (function template)