| Defined in header <algorithm> | ||
|---|---|---|
template< class InputIt1, class InputIt2 >
std::pair<InputIt1,InputIt2>
mismatch( InputIt1 first1, InputIt1 last1,
InputIt2 first2 ); | (1) | |
template< class InputIt1, class InputIt2, class BinaryPredicate >
std::pair<InputIt1,InputIt2>
mismatch( InputIt1 first1, InputIt1 last1,
InputIt2 first2,
BinaryPredicate p ); | (2) | |
template< class InputIt1, class InputIt2 >
std::pair<InputIt1,InputIt2>
mismatch( InputIt1 first1, InputIt1 last1,
InputIt2 first2, InputIt2 last2 ); | (3) | (since C++14) |
template< class InputIt1, class InputIt2, class BinaryPredicate >
std::pair<InputIt1,InputIt2>
mismatch( InputIt1 first1, InputIt1 last1,
InputIt2 first2, InputIt2 last2,
BinaryPredicate p ); | (4) | (since C++14) |
Returns the first mismatching pair of elements from two ranges: one defined by [first1, last1) and another defined by [first2,last2). If last2 is not provided (overloads (1,2)), it denotes first2 + (last1 - first1).
Overloads (1,3) use operator== to compare the elements, overloads (2,4) use the given binary predicate p.
Parameters
| first1, last1 | - | the first range of the elements |
| first2, last2 | - | the second range of the elements |
| p | - | binary predicate which returns true if the elements should be treated as equal. The signature of the predicate function should be equivalent to the following:
The signature does not need to have |
| Type requirements | ||
- InputIt1 must meet the requirements of InputIterator. | ||
- InputIt2 must meet the requirements of InputIterator. | ||
- BinaryPredicate must meet the requirements of BinaryPredicate. | ||
Return value
std::pair with iterators to the first two non-equivalent elements.
If no mismatches are found when the comparison reaches last1, the pair holds last1 and the corresponding iterator from the second range. The behavior is undefined if the second range is shorter than the first range. | (until C++14) |
If no mismatches are found when the comparison reaches last1 or last2, whichever happens first, the pair holds the end iterator and the corresponding iterator from the other range. | (since C++14) |
Complexity
last1 - first1 applications of operator== or the predicate p last1 - first1, last2 - first2) applications of operator== or the predicate p.Possible implementation
| First version |
|---|
template<class InputIt1, class InputIt2>
std::pair<InputIt1, InputIt2>
mismatch(InputIt1 first1, InputIt1 last1, InputIt2 first2)
{
while (first1 != last1 && *first1 == *first2) {
++first1, ++first2;
}
return std::make_pair(first1, first2);
} |
| Second version |
template<class InputIt1, class InputIt2, class BinaryPredicate>
std::pair<InputIt1, InputIt2>
mismatch(InputIt1 first1, InputIt1 last1, InputIt2 first2, BinaryPredicate p)
{
while (first1 != last1 && p(*first1, *first2)) {
++first1, ++first2;
}
return std::make_pair(first1, first2);
} |
| Third version |
template<class InputIt1, class InputIt2>
std::pair<InputIt1, InputIt2>
mismatch(InputIt1 first1, InputIt1 last1, InputIt2 first2, InputIt2 last2)
{
while (first1 != last1 && first2 != last2 && *first1 == *first2) {
++first1, ++first2;
}
return std::make_pair(first1, first2);
} |
| Fourth version |
template<class InputIt1, class InputIt2, class BinaryPredicate>
std::pair<InputIt1, InputIt2>
mismatch(InputIt1 first1, InputIt1 last1, InputIt2 first2, InputIt2 last2, BinaryPredicate p)
{
while (first1 != last1 && first2 != last2 && p(*first1, *first2)) {
++first1, ++first2;
}
return std::make_pair(first1, first2);
} |
Example
This program determines the longest substring that is simultaneously found at the very beginning of the given string and at the very end of it, in reverse order (possibly overlapping).
#include <iostream>
#include <string>
#include <algorithm>
std::string mirror_ends(const std::string& in)
{
return std::string(in.begin(),
std::mismatch(in.begin(), in.end(), in.rbegin()).first);
}
int main()
{
std::cout << mirror_ends("abXYZba") << '\n'
<< mirror_ends("abca") << '\n'
<< mirror_ends("aba") << '\n';
}Output:
ab a aba
See also
| determines if two sets of elements are the same (function template) | |
| (C++11) | finds the first element satisfying specific criteria (function template) |
| returns true if one range is lexicographically less than another (function template) | |
| searches for a range of elements (function template) | |
| std::experimental::parallel::mismatch
(parallelism TS) | parallelized version of std::mismatch (function template) |
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