unordered_set::equal_range

Finds range that matches a specified key.

std::pair<iterator, iterator>
    equal_range(const Key& keyval);
std::pair<const_iterator, const_iterator>
    equal_range(const Key& keyval) const;

Parameters

• keyval
  Key value to search for.

Remarks

The member function returns a pair of iterators X such that [X.first, X.second) delimits just those elements of the controlled sequence that have equivalent ordering with keyval. If no such elements exist, both iterators are end().

Example

// std_tr1__unordered_set__unordered_set_equal_range.cpp 
// compile with: /EHsc 
#include <unordered_set> 
#include <iostream> 
 
typedef std::unordered_set<char> Myset; 
int main() 
    { 
    Myset c1; 
 
    c1.insert('a'); 
    c1.insert('b'); 
    c1.insert('c'); 
 
// display contents " [c] [b] [a]" 
    for (Myset::const_iterator it = c1.begin(); 
        it != c1.end(); ++it) 
        std::cout << " [" << *it << "]"; 
    std::cout << std::endl; 
 
// display results of failed search 
    std::pair<Myset::iterator, Myset::iterator> pair1 = 
        c1.equal_range('x'); 
    std::cout << "equal_range('x'):"; 
    for (; pair1.first != pair1.second; ++pair1.first) 
        std::cout << " [" << *pair1.first << "]"; 
    std::cout << std::endl; 
 
// display results of successful search 
    pair1 = c1.equal_range('b'); 
    std::cout << "equal_range('b'):"; 
    for (; pair1.first != pair1.second; ++pair1.first) 
        std::cout << " [" << *pair1.first << "]"; 
    std::cout << std::endl; 
 
    return (0); 
    } 
 

 [c] [b] [a]
equal_range('x'):
equal_range('b'): [b]

Requirements

Header: <unordered_set>

Namespace: std

See Also

Reference

<unordered_set>

unordered_set Class