template <class InputIt, class T>
InputIt find(InputIt first, InputIt last, const T& value);

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<int> nums = {1, 2, 3, 4, 5};
    int target = 3;

    auto it = std::find(nums.begin(), nums.end(), target);
    if (it != nums.end()) {
        std::cout << "找到元素 " << target << ",位于索引 " << std::distance(nums.begin(), it) << std::endl;
    } else {
        std::cout << "未找到元素 " << target << std::endl;
    }

    return 0;
}

#include <iostream>
#include <string>
#include <algorithm>

int main() {
    std::string str = "Hello, world!";
    std::string substr = "world";

    auto it = std::find(str.begin(), str.end(), substr);
    if (it != str.end()) {
        std::cout << "找到子串 \"" << substr << "\",位于索引 " << std::distance(str.begin(), it) << std::endl;
    } else {
        std::cout << "未找到子串 \"" << substr << "\"" << std::endl;
    }

    return 0;
}