vector大小

简单的程序，测试vector的大小[c++]:

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#include <iostream.h>

#include <vector>

 

using namespace std;

 

struct Node

{

    int id;

    vector<int> score;

};

 

void DisplayVector(vector<int> &v)

{

    cout<<"sizeof(v) = "<<sizeof(v)<<endl;

    for(vector<int>::iterator it = v.begin(); it != v.end(); it++)

    {

        cout<<*it<<'\t';

    }

    cout<<endl;

}

 

void DisplaySize()

{

    cout<<"sizeof(vector<char>) = "<<sizeof(vector<char>)<<endl;

    cout<<"sizeof(vector<int>) = "<<sizeof(vector<int>)<<endl;

    cout<<"sizeof(vector<short>) = "<<sizeof(vector<short>)<<endl;

    cout<<"sizeof(vector<double>) = "<<sizeof(vector<double>)<<endl;

    cout<<"sizeof(vector<long>) = "<<sizeof(vector<long>)<<endl;

    cout<<"sizeof(vector<float>) = "<<sizeof(vector<float>)<<endl;

}

 

int main()

{

    DisplaySize();

 

    Node node;

    cout<<"sizeof(Node) = "<<sizeof(node)<<endl;

 

    node.id = 1;

    node.score.push_back(10);

    node.score.push_back(20);

    node.score.push_back(25);

    cout<<"sizeof(Node) = "<<sizeof(node)<<endl;

 

    DisplayVector(node.score);

 

    return 0;

}

输出结果：

sizeof(vector<char>) = 16
sizeof(vector<int>) = 16
sizeof(vector<short>) = 16
sizeof(vector<double>) = 16
sizeof(vector<long>) = 16
sizeof(vector<float>) = 16
sizeof(Node) = 20
sizeof(Node) = 20
sizeof(v) = 16
10      20      25

修改了下主函数：

int main()
{
 DisplaySize();

 Node node;
 cout<<"sizeof(Node)_1 = "<<sizeof(node)<<endl;

 node.id = 1;
 for(int i = 1; i <= 1000; i++)
 {
  node.score.push_back(i);
 }
 cout<<"sizeof(Node)_2 = "<<sizeof(node)<<endl; // 不管插入多少数据，sizeof(vector<>)大小不变

// DisplayVector(node.score);

 return 0;
}

发现“不管插入多少数据，sizeof(vector<>)大小不变，始终为16”!