c# - C# List 获得相同的值

Question

哦，请有人向我解释为什么会这样……

public List<EmployeeHeader> GetEmployees()
        {
            List<EmployeeHeader> eh = new List<EmployeeHeader>();
            string query = "SELECT " +
                           "     firstName, lastName " +
                           "FROM" +
                           "     tbEmployee ";

            DBConnect db = new DBConnect();
            DataTable dt = new DataTable();
            dt = db.getBD(query);

            int CountRows = dt.Rows.Count;

            EmployeeHeader emp = new EmployeeHeader();

            for(int i = 0; i < CountRows; i++)
            {
                emp.firstName = dt.Rows[i]["firstName"].ToString();
                emp.lastName = dt.Rows[i]["lastName"].ToString();
                eh.Add(emp);
            }

            return eh;

这是课程：

public class EmployeeHeader
    {
        public string firstName { get; set;}
        public string lastName {get; set;}

    }

最终结果是……

<ArrayOfEmployeeHeader xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www.istec.pt/">
<EmployeeHeader>
<firstName>Hugo</firstName>
<lastName>Almeida</lastName>
</EmployeeHeader>
<EmployeeHeader>
<firstName>Hugo</firstName>
<lastName>Almeida</lastName>
</EmployeeHeader>
<EmployeeHeader>
<firstName>Hugo</firstName>
<lastName>Almeida</lastName>
</EmployeeHeader>
<EmployeeHeader>
<firstName>Hugo</firstName>
<lastName>Almeida</lastName>
</EmployeeHeader>
<EmployeeHeader>
<firstName>Hugo</firstName>
<lastName>Almeida</lastName>
</EmployeeHeader>
</ArrayOfEmployeeHeader>

永远是同一个名字！！！我已经一步一步地调试，正确的名字进入了列表，但最后......我得到了相同的名字！

可能是一个愚蠢的错误，但请有人为我指出吗？

谢谢你

Answer 1

您正在设置同一实例的属性。将下面的行放入循环中：

EmployeeHeader emp = new EmployeeHeader();

Answer 2

        for(int i = 0; i < CountRows; i++)
        {
            EmployeeHeader emp = new EmployeeHeader();
            emp.firstName = dt.Rows[i]["firstName"].ToString();
            emp.lastName = dt.Rows[i]["lastName"].ToString();
            eh.Add(emp);
        }

Answer 3

像这样试试

for(int i = 0; i < CountRows; i++)
        {
            EmployeeHeader emp = new EmployeeHeader();
            emp.firstName = dt.Rows[i]["firstName"].ToString();
            emp.lastName = dt.Rows[i]["lastName"].ToString();
            eh.Add(emp);
        }