C++ txt 文件读取，并写入结构体中

wang 18 001 
li 19 002
zhao 20 003

代码如下：

#include
#include
#include
using  namespace  std;

struct  people
{
    string name;
    int  age;
    string id;
}p[20];

int  main()
{
    int  n = 0;
    ifstream in( "a.txt" , ios::in);
    if (!in.is_open())
    {
        cout <<  "Error: opening file fail"  << endl;
        exit (1);
    }
    while (!in.eof() && n < 20)
    {
        in >> p[n].name >> p[n].age >> p[n].id;
        n++;
    }

    //test
    for  ( int  i = 0; i < n; ++i)
        cout <<  "name:"  << p[i].name <<  " age:"  << p[i].age <<  " id:"  << p[i].id << endl;

    in.close();
    return  0;
}