C++ Programming Code Examples
C++ > Visual C++ 5.0 Standard C++ Library Code Examples
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
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Return first position where two ranges differ. Compares the elements in the range [first1,last1) with those in the range beginning at first2, and returns the first element of both sequences that does not match. C++ Algorithm mismatch() function compares both the containers to spot for any mismatch of values. The function returns the first element of both the containers that does not match. The elements are compared using operator== (or pred, in version (2)). The function shall not modify any of its arguments. This can either be a function pointer or a function object. Function returns a pair, where its members first and second point to the first element in both sequences that did not compare equal to each other.
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