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Algorithm mismatch - Search two sequences for a mismatched item.

Algorithm mismatch - Search two sequences for a mismatched item.


mismatch
	
 
Header
<algorithm>

template<class InputIterator1, class InputIterator2>
pair<InputIterator1, InputIterator2> mismatch(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2)

Search two sequences for a mismatched item. Compares corresponding pairs of elements from two ranges and returns the first mismatched pair.

The algorithm finds the first position at which a value in range [first1, last1) disagrees with the value in the range starting at first2. It returns a pair of iterators i and j such that i points into the range [first1, last1), and j points into the range beginning at first2. i and j should be equidistant from the beginning of their corresponding ranges.

The non-predicate version uses operator== for comparison.

template<class InputIterator1, class InputIterator2, BinaryPredicate pr>
pair<InputIterator1, InputIterator2> mismatch(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, BinaryPredicate pr)

Search two sequences for a mismatched item. Compares corresponding pairs of elements from two ranges and returns the first mismatched pair.

The algorithm finds the first position at which a value in range [first1, last1) disagrees with the value in the range starting at first2. It returns a pair of iterators i and j such that i points into the range [first1, last1), and j points into the range beginning at first2. i and j should be equidistant from the beginning of their corresponding ranges.

The predicate version uses predicate function pr for comparison.


Samples

#pragma warning (disable :4786)

#include <algorithm>
#include <iostream>
#include <string>
#include <utility>
#include <functional>

int main()
{
	int set1[5] = {10, 15, 20, 25, 30} ;
	int set2[4] = {10, 15, 25, 30} ;

	std::ostream_iterator<int> intOstreamIt(std::cout, ", ") ;

	std::cout << "set1 = " ;
	std::copy(set1, set1+5, intOstreamIt) ;
	std::cout << std::endl ;

	std::cout << "set2 = " ;
	std::copy(set2, set2+4, intOstreamIt) ;
	std::cout << std::endl ;

	std::pair<int*, int*> pi ;
	
	//non-predicate version of mismatch
	std::cout << "\n\nusing non-predicate version of mismatch" << std::endl ;
	pi = std::mismatch(set1, set1+5, set2) ;
	std::cout << "first mismatched element in set1 = " << *(pi.first) << std::endl ;
	std::cout << "first mismatched element in set2 = " << *(pi.second) << std::endl ;

	//predicate version of mismatch
	std::cout << "\n\nusing predicate version of mismatch" << std::endl ;
	pi = std::mismatch(set1, set1+5, set2, std::equal_to<int>()) ;
	std::cout << "first mismatched element in set1 = " << *(pi.first) << std::endl ;
	std::cout << "first mismatched element in set2 = " << *(pi.second) << std::endl ;


	return 0 ;
}

Program Output

set1 = 10, 15, 20, 25, 30,
set2 = 10, 15, 25, 30,


using non-predicate version of mismatch
first mismatched element in set1 = 20
first mismatched element in set2 = 25


using predicate version of mismatch
first mismatched element in set1 = 20
first mismatched element in set2 = 25