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##### equal

###### Prototype

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

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

###### Description

`equal` returns `true` if `distance(rng1)` is equal to the `distance(rng2)` and for each element `x` in `rng1`, the corresponding element `y` in `rng2` is equal. Otherwise `false` is returned.

In this range version of `equal` it is perfectly acceptable to pass in two ranges of unequal lengths.

Elements are considered equal in the non-predicate version if `operator==` returns `true`. Elements are considered equal in the predicate version if `pred(x,y)` is `true`.

###### Definition

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

###### Requirements

For the non-predicate versions:

- `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 `EqualityComparableConcept`.
- `SinglePassRange2`'s value type is a model of the `EqualityComparableConcept`.
- `SinglePassRange1`'s value type can be compared for equality with `SinglePassRange2`'s value type.

For the predicate versions:

- `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.

###### Complexity

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