c++ primer chapter 16.4-526互联

/*
 #include <iostream>
#include <string>
#include <vector>
#include <list>
using namespace  std;
template <typename I, typename T>
I find(I b, I e, const T &v) {
   while (b != e && *b != v) {
      b++;
   return b;
   }
}

int main() {
   vector<int> vi = {0, 2, 4, 6, 8, 10};
   list<string> ls = { "Hello", "World", "!" };

   auto iter = find(vi.begin(), vi.end(), 6);
    //vector<int> iter = find(vi.begin(), vi.end(), 6);

    if (iter == vi.end())
      std::cout << "find 6 at position" << std::endl;
   else
      std::cout << "find 6 at position" << iter - vi.begin() << std::endl;

   auto iter1 = find(ls.begin(), ls.end(), "mom");
    //list<string> iter1 = find(ls.begin(), ls.end(), "mom");

    if (iter == ls.end()) {
      std::cout << "can't find mom" << std::endl;
   }
   else
      std::cout << "found mom" << std::endl;

   return 0;

}
 */
#include <iostream>
#include <vector>
#include <list>

using namespace std;

template <typename I, typename T>
I find(I beg, I end, T val)
{
    auto iter = beg;
    for (; iter != end; ++iter)
        if (*iter == val)
            break;
    return iter;
}

int main()
{
    vector<int> iv = {1, 2, 3, 4, 5};
    list<string> slst = {"dog", "cat", "rat"};

    auto p1 = find(iv.begin(), iv.end(), 4);
    if (p1 != iv.end())
        cout << *p1 << endl;

    auto p2 = find(slst.begin(), slst.end(), "rat");
    if (p2 != slst.end())
        cout << *p2 << endl;

    return 0;
}