C#(对象数组)对象引用未设置为对象的实例

Question

我在这一行得到了对象引用错误:emp [count] .emp_id = int.Parse(parts [0]);

在这段代码中

这个程序从文件中读取并存储在对象数组中

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    public class employees
    {
        public int emp_id;
        public string firstName;
        public string lastName;
        public double balance;
    }

    private void btnOpen_Click(object sender, EventArgs e)
    {
        OpenFileDialog file = new OpenFileDialog();
        DialogResult result = file.ShowDialog();
        if (result == DialogResult.Cancel) return;

        string fileName = file.FileName;
        StreamReader reader = new StreamReader(fileName);

        string[] lines = File.ReadAllLines(fileName);
        int emp_count = lines.Count<string>();
        employees[] emp = new employees[emp_count];
        int count = 0;
        foreach (string line in lines)
        {
            string[] parts = new string[4];
            parts = line.Split(',');
            **emp[count].emp_id = int.Parse(parts[0]);**
            emp[count].firstName = parts[1];
            emp[count].lastName = parts[2];
            emp[count].balance = double.Parse(parts[3]);
            count++;
            txtGet.Text += emp[count].emp_id + " " + emp[count].firstName + " " + emp[count].lastName + " " + emp[count].balance + " \n ";

        }

Answer 1

你需要初始化emp[count]一些东西.

您可以通过添加以下内容来执行此操作:

foreach (string line in lines) 
{ 
    emp[count] = new employees();
    string[] parts = new string[4]; 
    //....
}

当你打电话给employees[] emp = new employees[emp_count];你时,初始化emp为一个employees长度为的数组emp_count.

emp[0] = null;
emp[1] = null;
//etc.

内部的每个元素emp也需要在使用之前进行实例化.