<C++ Primer_5th>习题_3.24

//读入一组整数并把它们存入一个vector对象，将每对相邻整数的和输出出来。//使用迭代器实现#include<iostream>#include<vector>using namespace std;int main(){vector<int> v_int;int i_val;cout << "请输入一组数字: " << endl;while (cin >> i_val)v_int.push_back(i_val);if(v_int.cbegin() == v_int.cend())     //if (v_int.size() == 0){cout << "没有任何元素  " << endl;system("pause");return -1;}cout << "相邻两项的和依次是:  " << endl;//奇数项if(v_int.size() % 2 != 0){ for (auto it = v_int.cbegin(); it != v_int.cend() - 1; ++it){//输出两项和cout << (*it + *(++it)) << "  ";//每行输出5个数字if ((it - v_int.cbegin() + 1) % 10 == 0)cout << endl;}//如果元素个数是奇数，单独处理最后一个元素if (v_int.size() % 2 != 0)cout << *(v_int.cend() - 1) << endl;}//偶数项else{for (auto it = v_int.cbegin(); it != v_int.cend(); ++it){//输出两项和cout << (*it + *(++it)) << "  ";//每行输出5个数字if ((it - v_int.cbegin() + 1) % 10 == 0)cout << endl;}}    cout << endl;    system("pause");return  0;}//求首尾元素和的程序/*#include<iostream>#include<vector>using namespace std;int main(){vector<int> v_int;int i_val;cout << "请输入一组数字: " << endl;while (cin >> i_val)v_int.push_back(i_val);if (v_int.cbegin() == v_int.cend()){cout << "没有任何元素: " << endl;system("pause");return 0;}cout << "首尾两项的和依次是： " << endl;auto beg = v_int.cbegin();auto end = v_int.cend();auto mid = beg+(end - beg) / 2;         //若写成这样auto mid = (end - beg) / 2是错的for (auto it = beg; it !=mid ; ++it){cout << (*it + *(beg + (end - it) - 1)) << " ";if ((it - beg + 1) % 5 == 0)cout << endl;}if (v_int.size() % 2 != 0)cout << *(beg + (end - beg) / 2);cout << endl;system("pause");return 0;}*/