技術標籤：C++

一、介紹

mismatch演算法：

template <class InputIterator1, class InputIterator2>
  pair<InputIterator1, InputIterator2>
    mismatch (InputIterator1 first1, InputIterator1 last1, InputIterator2 first2 )
{
  while ( (first1!=last1) && (*first1==*first2) )  // or: pred(*first1,*first2), for version 2
  { ++first1; ++first2; }
  return std::make_pair(first1,first2);
}
 

mismatch演算法會拿著 [frist1,last1) 中的值和[first2,last2)中的元素進行比較，並且返回第一個找到的兩個區間中不相等的值，並且返回指向這兩個不相等元素的 std::pair。

二、用法

例項1：尋找兩個陣列中，第一個相等的元素和第一個不相等的元素

// not2 example
#include <iostream>     // std::cout
#include <functional>   // std::not2, std::equal_to
#include <algorithm>    // std::mismatch
#include <utility>      // std::pair

int main () {
  int foo[] = {10,20,30,40,50};
  int bar[] = {0,15,30,45,60};
  std::pair<int*,int*> firstmatch；
  std::pair<int*,int*> firstmismatch;
  firstmismatch = std::mismatch (foo, foo+5, bar, std::equal_to<int>());
  firstmatch = std::mismatch (foo, foo+5, bar, std::not2(std::equal_to<int>()));
  std::cout << "First mismatch in bar is " << *firstmismatch.second << '\n';
  std::cout << "First match in bar is " << *firstmatch.second << '\n';
  return 0;
}
 

例項2

#include <iostream>     // std::cout
#include <algorithm>    // std::mismatch
#include <vector>       // std::vector
#include <utility>      // std::pair
 
bool mypredicate (int i, int j) {
  return (i==j);
}
 
int main () {
  std::vector<int> myvector;
  for (int i=1; i<6; i++) myvector.push_back (i*10); // myvector: 10 20 30 40 50
 
  int myints[] = {10,20,80,320,1024};  //   myints: 10 20 80 320 1024
 
  std::pair<std::vector<int>::iterator,int*> mypair;
 
  // using default comparison:
  mypair = std::mismatch (myvector.begin(), myvector.end(), myints);
  std::cout << "First mismatching elements: " << *mypair.first;
  std::cout << " and " << *mypair.second << '\n';
 
  ++mypair.first; ++mypair.second;
 
  // using predicate comparison:
  mypair = std::mismatch (mypair.first, myvector.end(), mypair.second, mypredicate);
  std::cout << "Second mismatching elements: " << *mypair.first;
  std::cout << " and " << *mypair.second << '\n';
 
  return 0;
}
 

參考：

https://blog.csdn.net/qq_21441793/article/details/79293729

https://www.cnblogs.com/working-in-heart/p/12231635.html