[/
    Copyright 2010 Neil Groves
    Distributed under the Boost Software License, Version 1.0.
    (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
/]
[section:lexicographical_compare lexicographical_compare]

[heading Prototype]

``
template<
    class SinglePassRange1,
    class SinglePassRange2
    >
bool lexicographical_compare(const SinglePassRange1& rng1,
                             const SinglePassRange2& rng2);

template<
    class SinglePassRange1,
    class SinglePassRange2,
    class BinaryPredicate
    >
bool lexicographical_compare(const SinglePassRange1& rng1,
                             const SinglePassRange2& rng2,
                             BinaryPredicate pred);    
``

[heading Description]

`lexicographical_compare` compares element by element `rng1` against `rng2`. If the element from `rng1` is less than the element from `rng2` then `true` is returned. If the end of `rng1` without reaching the end of `rng2` this also causes the return value to be `true`. The return value is `false` in all other circumstances. The elements are compared using `operator<` in the non-predicate versions of `lexicographical_compare` and using `pred` in the predicate versions.

[heading Definition]

Defined in the header file `boost/range/algorithm/lexicographical_compare.hpp`

[heading Requirements]

[*For the non-predicate versions of lexicographical_compare:]

* `SinglePassRange1` is a model of the __single_pass_range__ Concept.
* `SinglePassRange2` is a model of the __single_pass_range__ Concept.
* `SinglePassRange1`'s value type is a model of the `LessThanComparableConcept`.
* `SinglePassRange2`'s value type is a model of the `LessThanComparableConcept`.
* Let `x` be an object of `SinglePassRange1`'s value type. Let `y` be an object of `SinglePassRange2`'s value type. `x < y` must be valid. `y < x` must be valid.

[*For the predicate versions of lexicographical_compare:]

* `SinglePassRange1` is a model of the __single_pass_range__ Concept.
* `SinglePassRange2` is a model of the __single_pass_range__ Concept.
* `BinaryPredicate` is a model of the `BinaryPredicateConcept`.
* `SinglePassRange1`'s value type is convertible to `BinaryPredicate`'s first argument type.
* `SinglePassRange2`'s value type is convertible to `BinaryPredicate`'s second argument type.

[heading Complexity]

Linear. At most `2 * min(distance(rng1), distance(rng2))` comparisons.

[endsect]