Difference between revisions of "cpp/algorithm/mismatch"
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===Possible implementation=== | ===Possible implementation=== | ||
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template<class InputIterator1, class InputIterator2> | template<class InputIterator1, class InputIterator2> | ||
Revision as of 04:14, 3 July 2012
Template:ddcl list begin <tr class="t-dsc-header">
<td><algorithm>
<td></td> <td></td> </tr> <tr class="t-dcl ">
<td >std::pair<InputIterator1,InputIterator2>
mismatch( InputIterator1 first1,
InputIterator1 last1,
<td > (1) </td> <td class="t-dcl-nopad"> </td> </tr> <tr class="t-dcl ">
<td >std::pair<InputIterator1,InputIterator2>
mismatch( InputIterator1 first1,
InputIterator1 last1,
InputIterator2 first2,
<td > (2) </td> <td class="t-dcl-nopad"> </td> </tr> Template:ddcl list end
Returns the first mismatching pair of elements from two ranges: one defined by [first1, last1) and another starting at first2. The first version of the function uses operator== to compare the elements, the second version uses the given binary predicate p.
Contents |
Parameters
| first1, last1 | - | the first range of the elements |
| first2 | - | the beginning of 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: bool pred(const Type1 &a, const Type2 &b); While the signature does not need to have const &, the function must not modify the objects passed to it and must be able to accept all values of type (possibly const) |
Return value
std::pair with iterators to the first two non-equivalent elements, or, if no different elements found, pair with last1 and the corresponding iterator from the second range.
Complexity
At most last1 - first1 applications of the predicate
Possible implementation
| First version |
|---|
template<class InputIterator1, class InputIterator2> std::pair<InputIterator1, InputIterator2> mismatch(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2) { while (first1 != last1 && *first1 == *first2) { ++first1, ++first2; } return std::make_pair(first1, first2); } |
| Second version |
template<class InputIterator1, class InputIterator2, class BinaryPredicate> std::pair<InputIterator1, InputIterator2> mismatch(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, BinaryPredicate p) { while (first1 != last1 && p(*first1, *first2)) { ++first1, ++first2; } return std::make_pair(first1, first2); } |
Example
This program determines the 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
