#include <iostream>
#include <vector>
using namespace std;
int main ()
{
    vector<int> myvector;
    
    // set some initial content:
    for (int i=1;i<10;i++) myvector.push_back(i);//長度為9
    
    myvector.resize(5);//重新設定長度為5，多餘的元素刪掉
    myvector.resize(8,100);//重新設定長度為8，填充元素為100
 

    myvector.resize(12);//預設填充的元素是0
    
    cout << "myvector contains:";
    for (int i=0;i<myvector.size();i++)
        cout << ' ' << myvector[i];
    cout << '\n';
    
    return 0;
}

輸出

myvector contains: 1 2 3 4 5 100 100 100 0 0 0 0