Check two sequences for element by element equality

Source code

Declaration

template <class InputIterator1, class InputIterator2>
inline bool equal(InputIterator1 first1, InputIterator1 last1,
                  InputIterator2 first2);

template <class InputIterator1, class InputIterator2, class BinaryPredicate>
bool equal(InputIterator1 first1, InputIterator1 last1,
           InputIterator2 first2, BinaryPredicate binary_pred);

Description  Each equal  function returns true (i.e., a non-zero value) if the range [ first1, last1) and the range of size n beginning at first2 , where n is the size of the range [ first1, last1) , contain the same elements  in the same order , false (i.e., 0) otherwise. In the first function checks for element equality are made with operator==, while in the second they are made with the function object binary_pred.

Type requirements

• InputIterator1 and InputIterator2 must be at least input iterators .
• BinaryPredicate must be a function object type that provides int operator()(T1, T2), where T1 and T2 are the dereference types of InputIterator1 and InputIterator2, respectively.

Group Non-mutating sequence operations.

Time complexity Linear.

If the two sequences are not equal  element by element, then the number of equality operations performed is the size of the range [ first1, i] , where i is the iterator referring to the first element in the range [ first1, last1) that does not match the corresponding element  in the rangE the range of size n beginning at first2 ; otherwise, the number of equality operations performed is the size of the range [ first1, last1) .

Space complexity Constant.

Mutative? No.

Glossary terms BinaryPredicate, constant space, dereference type, function object, function object type, InputIterator, iterator, linear time, mutative, operator ==, predicate, range, sequence.

Example Select here to view the source code for the example.

Implementation Select here to view source code (Copyright (C) 1994, Hewlett-Packard Company) for this algorithm.