vector大小
简单的程序,测试vector的大小[c++]:
#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”!
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