vector 简介

vector也是容器的一种，里面可以存放相同类型的元素，string容器存放的是char类型元素，若是存放其他类型元素，如：int ,double, 自定义类等类型。

vector 构造

定义方式如下:

void VectDefine() {    vector
    
      vec1;    vector
     
       vec2(5,12);    for (vector
      
       ::iterator iter = vec2.begin(); iter != vec2.end(); ++iter) {        cout << *iter << endl;    }    cout << "*****************" << endl;    for each (int value in vec2)    {        cout << value << endl;    }}
      
     
    

vector 容量

void VectCapacity() {    vector
    
      vec1;    cout << vec1.capacity() << endl;// 默认为0    vector
     
       vec2(5,222);// 初始化为5个0    cout << vec2.size() << " " << vec2.capacity() << endl;    vec2.resize(3);    cout << vec2.size() << " " << vec2.capacity() << endl;    //cout << vec2[3];// resize()重置原size大小，被裁切的元素被释放掉，通过此行代码访问会崩溃    vector
      
       ::iterator iter = vec2.begin();    cout << vec2.capacity() << endl;// 当前空间为5    cout << "--" << *iter << endl;    vec2.push_back(12);    iter = vec2.begin();// 这里同样要注意迭代器失效的问题    cout << "--" << *iter << endl;    cout << vec2.capacity() << endl;// 新增1个元素，空间为7，5 + 5 / 2    vec2.push_back(12);    vec2.push_back(12);    vec2.push_back(12);    cout << vec2.capacity() << endl; 新增3个元素，空间为10，7 + 7 / 2    // vc6.0是以2倍增加}
      
     
    

vector 输出

void VectCout() {    vector
    
      vec1;    for (int i = 0; i < 10; ++i) {        vec1.push_back(i);    }    for (int i = 0; i < vec1.size(); ++i) {        cout << vec1[i] << "  " << vec1.at(i) << endl;    }// at()会抛出异常，[]下标的方式不会}
    

vector 修改

void VectChange() {    // assign()    vector
    
      vec1;    vector
     
       vec2;    vector
      
        vec3;    for (int i = 0; i < 10; ++i) {        vec1.push_back(i);    }    vector
       
        ::iterator iter_start = vec1.begin() + 2;    vector
        
         ::iterator iter_end = vec1.end() - 2;    vec2.assign(iter_start, iter_end);    for (int i = 0; i < vec2.size(); ++i) {        cout << vec2.at(i) << endl;// 输出2 3 4 5 6 7    }    vec3.assign(5, 333);    for (int i = 0; i < vec3.size(); ++i) {        cout << vec3.at(i) << endl;//输出5个333    }    //clear()/empty()/erase()    vec1.clear();    cout << "size:" <
         
          << endl; cout << "is empty：" << vec1.empty() << endl;// 输出is empty：1 vec2.erase(vec2.begin() + 2); for (int i = 0; i < vec2.size(); ++i) { cout << vec2.at(i) << endl;// 输出2 3 5 6 7 } vec2.erase(vec2.begin() + 2, vec2.end() - 1); for (int i = 0; i < vec2.size(); ++i) { cout << vec2.at(i) << endl;// 输出2 3 7 } //insert vec3.insert(vec3.begin() + 1, 444); for (int i = 0; i < vec3.size(); ++i) { cout << vec3.at(i) << endl;// 输出333 444 333 333 333 333 } cout << endl; vec3.insert(vec3.begin() + 1, 2, 555); for (int i = 0; i < vec3.size(); ++i) { cout << vec3.at(i) << endl;// 输出333 555 555 444 333 333 333 333 } cout << endl; vec3.insert(vec3.begin() + 1, vec2.begin(), vec2.end()); for (int i = 0; i < vec3.size(); ++i) { cout << vec3.at(i) << endl;// 输出333 2 3 7 555 555 444 333 333 333 333 }}