vector容器成员函数resize与reserve的区别

resize是设置向量的大小：即向量的大小与容量相同。而reserve是设置向量的容量，并不改变向量的大小。另外：向量的最大大小是固定住，不可改变。例子：

#include
"stdafx.h"
#include
<iostream>
#include
<vector>
 
using namespace std;
 
typedefvector<int> VEC_INT;
int_tmain(int argc, _TCHAR* argv[])
{
    VEC_INTthevec;
    cout<<"before insert data:"<<endl;
    cout<<"the size of vector:"<<thevec.size()<<endl;
    cout<<"the capasity of vector:"<<thevec.capacity()<<endl;
    cout<<"the max size of vector:"<<thevec.max_size()<<endl;
    cout<<"after insert data:"<<endl;
    thevec.push_back(42);
    cout<<"the size of vector:"<<thevec.size()<<endl;
    cout<<"the capasity of vector:"<<thevec.capacity()<<endl;
    cout<<"the max size of vector:"<<thevec.max_size()<<endl;
 
    thevec.reserve(100);
    cout<<"After reserve (100):"<<endl;
    cout<<"the size of vector:"<<thevec.size()<<endl;
    cout<<"the capasity of vector:"<<thevec.capacity()<<endl;
    cout<<"the max size of vector:"<<thevec.max_size()<<endl;
 
    thevec.resize(1000);
    cout<<"After resize (1000):"<<endl;
    cout<<"the size of vector:"<<thevec.size()<<endl;
    cout<<"the capasity of vector:"<<thevec.capacity()<<endl;
    cout<<"the max size of vector:"<<thevec.max_size()<<endl;
    return 0;
}

运行结果：



可以看出：默认情况下，向量的大小和容量是相同的，如果用resize改变向量的大小，则同时改变了向量的容量。