在std::vector中查找索引

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

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

    auto it = std::find(vec.begin(), vec.end(), target);
    if (it != vec.end()) {
        int index = std::distance(vec.begin(), it);
        std::cout << "Index of " << target << " is " << index << std::endl;
    } else {
        std::cout << "Element not found" << std::endl;
    }

    return 0;
}

Index of 3 is 2

#include <iostream>
#include <vector>

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

    int index = -1;
    for (int i = 0; i < vec.size(); i++) {
        if (vec[i] == target) {
            index = i;
            break;
        }
    }

    if (index != -1) {
        std::cout << "Index of " << target << " is " << index << std::endl;
    } else {
        std::cout << "Element not found" << std::endl;
    }

    return 0;
}

Index of 3 is 2