std::min() algorithm
- od C++14
- od C++11
- do C++11
// (1)
template< class T >
constexpr const T& min( const T& a, const T& b );
// (2)
template< class T, class Compare >
constexpr const T& min( const T& a, const T& b, Compare comp );
// (3)
template< class T >
constexpr T min( std::initializer_list<T> ilist );
// (4)
template< class T, class Compare >
constexpr T min( std::initializer_list<T> ilist, Compare comp );
// (1)
template< class T >
const T& min( const T& a, const T& b );
// (2)
template< class T, class Compare >
const T& min( const T& a, const T& b, Compare comp );
// (3)
template< class T >
T min( std::initializer_list<T> ilist );
// (4)
template< class T, class Compare >
T min( std::initializer_list<T> ilist, Compare comp );
// (1)
template< class T >
const T& min( const T& a, const T& b );
// (2)
template< class T, class Compare >
const T& min( const T& a, const T& b, Compare comp );
Returns the smaller of the given values.
- (1 - 2) Returns the smaller of
a
andb
. - (3 - 4) Returns the smallest of the values in initializer list
ilist
.
Parameters
a b | The values to compare. |
ilist | Initializer list with the values to compare. |
cmp | Comparison function object (i.e. an object that satisfies the requirements of Compare) which returns
While the signature does not need to have The types |
Type requirements
-
(1, 3):
T
LessThanComparable -
(3 - 4):
T
CopyConstructible
Return value
- (1 - 2) The smaller of
a
andb
, according to the projection. If they are equivalent, returnsa
. - (3 - 4) The smallest value in
ilist
. If several values are equivalent to the smallest, returns the leftmost such value.
Complexity
- (1 - 2) Exactly one comparison.
- (3 - 4) Exactly
ilist.size() - 1
comparisons.
Exceptions
(none)
Possible implementation
min (1)
template<class T>
const T& min(const T& a, const T& b)
{
return (b < a) ? b : a;
}
min (2)
template<class T, class Compare>
const T& min(const T& a, const T& b, Compare comp)
{
return (comp(b, a)) ? b : a;
}
min (3)
template<class T>
T min(std::initializer_list<T> ilist)
{
return *std::min_element(ilist.begin(), ilist.end());
}
min (4)
template<class T, class Compare>
T min(std::initializer_list<T> ilist, Compare comp)
{
return *std::min_element(ilist.begin(), ilist.end(), comp);
}
Notes
Capturing the result of std::min
by reference produces a dangling reference if one of the parameters is a temporary and that parameter is returned:
int n = 1;
const int& r = std::min(n - 1, n + 1); // r is dangling
Examples
#include <algorithm>
#include <iostream>
#include <string_view>
int main()
{
std::cout << "smaller of 1 and 9999 is " << std::min(1, 9999) << '\n'
<< "smaller of 'a', and 'b' is '" << std::min('a', 'b') << "'\n"
<< "shortest of \"foo\", \"bar\", and \"hello\" is \""
<< std::min({"foo", "bar", "hello"},
[](const std::string_view s1, const std::string_view s2)
{
return s1.size() < s2.size();
}) << "\"\n";
}
smaller of 1 and 9999 is 1
smaller of 'a', and 'b' is 'a'
shortest of "foo", "bar", and "hello" is "foo"
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