stl vector创建二维数组

 1 vector<vector<int>> v(5);
 2     for (auto it = v.begin(); it != v.end(); it++)
 3     {
 4         static int num = 0;
 5         (*it).reserve(5);//预留空间为5，但此时vector<int>的元素数量为0，下面这段jt=end()
 6     /*    for (auto jt = (*it).begin(); jt != (*it).end(); jt++,num++)
 7         {
 8             *jt = num;
 9         }*/
10         for (int j = 0; j < (*it).capacity(); j++, num++)
11             (*it).push_back(num);
12     }
13     for (auto it = v.begin(); it != v.end(); it++)
14     {
15         
16         for (auto jt = (*it).begin(); jt != (*it).end(); jt++)
17         {
18             cout << *jt << " ";
19         }
20     }
21     for (int i = 0; i < v.size(); i++)
22     {
23         for (int j = 0; j < v[0].size(); j++)
24         {
25             cout << v[i][j] << " ";
26         }
27     }

创建了一个5*5的二维数组，如果需要还可以扩容；行1声明了含有5个vector<int>的元素，每个元素已经用改类型的默认初始化方式初始化了，vector<int>的默认初始化为一个空vector;　　cout << v[0].size() << " " << v[0].capacity() << endl; 

 

转载于:https://www.cnblogs.com/hchacha/p/7666256.html