Vector元素的遍历和修改

/************************************************************************* > File Name: vector.cpp > Author: > Mail: > Created Time: Thu 13 Apr 2017 08:57:25 PM CST ************************************************************************/ #include<iostream> #include<vector> using namespace std; int main() { vector<int> ivec; for(int i = 0; i < 10; ++i) ivec.push_back(i); //遍历vector元素 //1: 利用迭代器 for(auto it = ivec.begin(); it != ivec.end(); ++it) cout<<*it<<" "; cout<<endl; //2: 利用下标操作符 for(auto i = 0; i < ivec.size(); ++i) cout<<ivec[i]<<" "; cout<<endl; //3: 利用范围for循环 for(auto i : ivec) cout<<i<<" "; cout<<endl<<endl; //修改vector中的元素（前提条件是vector中已有元素，且以下方式均不能改变已有元素的个数） //1: 利用迭代器 for(auto it = ivec.begin(); it != ivec.end(); ++it) { *it = *it * 2; cout<<*it<<" "; } cout<<endl; //2: 利用下标操作符 for(auto i = 0; i < ivec.size(); ++i) { ivec[i] = ivec[i] * 2; cout<<ivec[i]<<" "; } cout<<endl; //3: 利用范围for循环 for(auto &i : ivec)//注意此处是引用 { i = i * 2; cout<<i<<" "; } cout<<endl; return 0; }