vector的capacity增长方式

vector的capacity()调用返回vector中最大能够存储的元素个数，也即在下一次需要扩充容量之前能容纳的元素个数。reserve会使容器在必要的时候增长，以便容纳制指定数目的元素。

#include <iostream>
#include <vector>
using namespace std;
int main()
{
    vector<int> u;
    cout << "Initial capaciry of u: " << u.capacity() << "\n";
    for(int i = ; i < ; ++i)
    {
        u.push_back(i);
        cout<<"size is "<<u.size()<<" ";
        cout<<"Now capacity is :" << u.capacity() << "\n";
    }
    return ;
}

运行环境：win7 32bit codeblocks

Initial capaciry of u:
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