| 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:
The signature does not need to have |
| 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 comparisonsPossible 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
#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
| returns the smaller of the given values (function template) | |
| returns the greater of the given values (function template) | |
| (C++11) | returns the smallest and the largest element in a range (function template) |
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