vector&list 效率比较

转自：https://www.cnblogs.com/wllwqdeai/p/13441463.html

1、比较代码（https://blog.csdn.net/libaoshan55/article/details/77337878）

int main() {
    cout << "Test vector and list time" << endl;
    int N = 10000;
    int count = 0;
    while (count <= 3) {
        vector<int> vecInt;
        list<int> listInt;
        clock_t start, finish;
        cout << "N==" << N << endl;
        start = clock();
        for (int i = 0; i < N; ++i) {
            vecInt.push_back(i);
        }
        finish = clock();
        cout << "vector push_back 时间为" << (finish - start) << "毫秒" << endl;
        //insert time
        vector<int>::iterator pos_vec = vecInt.begin();
        ++pos_vec;
        vecInt.insert(pos_vec, 99);
        finish = clock();
        cout << "vector insert 时间为" << (finish - start) << "毫秒" << endl;


        start = clock();
        for (int i = 0; i < N; ++i) {
            listInt.push_back(i);
        }
        finish = clock();
        cout << "list push_back 时间为" << (finish - start) << "毫秒" << endl;

        //insert time
        start = clock();
        list<int>::iterator pos_ls = listInt.begin();
        ++pos_ls;
        listInt.insert(pos_ls, 99);
        finish = clock();
        cout << "list insert 时间为" << (finish - start) << "毫秒" << endl;

        //vector<int>::iterator iter = vecInt.begin();
        //start = clock();
        //for (; iter!=vecInt.end(); ++iter) {
        //    *iter;
        //}
        //finish = clock();
        //cout << "vector'iterator 访问元素时间为 " << (finish - start) << "毫秒" << endl;
        //start = clock();
        //for (int i = 0; i < vecInt.size(); ++i) {
        //    vecInt[i];
        //}
        //finish = clock();
        //cout << "vector'[] 访问元素时间为 " << (finish - start) << "毫秒" << endl;

        //start = clock();
        //for (list<int>::iterator iter = listInt.begin(); iter != listInt.end(); ++iter) {
        //    *iter;
        //}
        //finish = clock();
        //cout << "list 访问元素时间为 " << (finish - start) << "毫秒" << endl;

        ++count;
        N *= 10;
        vecInt.clear();
        listInt.clear();
        cout << vecInt.capacity() << endl;

    }
}

2、vector下标[ ]与迭代器iterator遍历效率比较结果：[ ]是iterator的十倍； 

3、list与vector迭代器遍历效率比较：差不多

4、list与vector的push_back()效率比较：vector远超list

5、list与vector的insert()效率比较：vector效率远低于list，根本不是一个数量级

总结：

1、vector遍历能用[ ] 不用迭代器

2、插入操作多时使用list