std::equal_range

Template:cpp/algorithm/sidebar Template:ddcl list begin

Defined in header <algorithm>

template< class ForwardIterator, class T >
std::pair<ForwardIterator,ForwardIterator> 
    equal_range( ForwardIterator first, ForwardIterator last,
                 const T& value );

(1)

template< class ForwardIterator, class T, class Compare >
std::pair<ForwardIterator,ForwardIterator> 
    equal_range( ForwardIterator first, ForwardIterator last,
                 const T& value, Compare comp );

(2) Template:ddcl list end Returns a range containing all elements equal to value in the sorted range [first, last). The range is defined by two iterators, one pointing to the first element that is not less than value and another pointing to the first element greater than value. The first iterator may be alternatively obtained with lower_bound(), the second - with upper_bound(). The first version uses Template:cpp to compare the elements, the second version uses the given comparison function comp. Template:params

first, last - the range of elements to examine

value - value to compare the elements to

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);

While the signature does not need to have const&, the function must not modify the objects passed to it and must be able to accept all values of type (possibly const) Type1 and Type2 regardless of value category (thus, Type1& is not allowed, nor is Type1 unless for Type1 a move is equivalent to a copy(since C++11)).
The types Type1 and Type2 must be such that an object of type T can be implicitly converted to both Type1 and Type2, and an object of type ForwardIterator can be dereferenced and then implicitly converted to both Type1 and Type2.

Template:returns Template:cpp containing a pair of iterators defining the wanted range, the first pointing to the first element that is not less than value and the second pointing to the first element greater than value.

If there are no elements not less than value, last is returned as the first element. Similarly if there are no elements greater than value, last is returned as the second element

Template:complex

logarithmic in the distance between first and last

Template:eq fun cpp

Template:example cpp

Template:see also

Template:cpp/algorithm/dcl list lower bound Template:cpp/algorithm/dcl list upper bound Template:cpp/algorithm/dcl list binary search