c# - 如何在 C# 中将属性作为参数传递？

Question

我需要在 C# 中的同一对象类型中使用 4 个不同的属性来实现排序。

假设对象 Student 有姓名、ID、出生日期和年级。我如何重用代码来对它们进行排序。我已成功按名称排序，如何重用代码？

private void btnSortName_Click(object sender, EventArgs e)
    {
        Student obj = new Student();
        List<Student> listOfStudents = obj.List();
        int student_count = listOfStudents.Count();
        int first_index, last_index;

        for (first_index = 1; first_index < student_count; first_index++)
        {
            last_index = first_index - 1;
            Student first = listOfStudents[first_index];
            Student last = listOfStudents[last_index];

            while (last_index >= 0 && DateTime.Compare(last.RDate, first.RDate) > 0)
            {
                listOfStudents[last_index + 1] = listOfStudents[last_index];
                last_index = last_index - 1;
            }
            listOfStudents[last_index + 1] = first;
        }
        DataTable dt = Utility.ConvertToDataTable(listOfStudents);
        dataGridStudents.DataSource = dt;
        btnSortName.Visible = false;
        btnSortName.Enabled = false;
        btnSortNameD.Visible = true;
        btnSortNameD.Enabled = true;
    }

我尝试通过创建插入排序方法并将属性作为参数传递并返回该对象的列表来执行此操作，但这两个都显示错误:

public List<Student> insertion_Sort(ref String data, Boolean asc)
    {
        Student obj = new Student();
        List<Student> listOfStudents = obj.List();
        int student_count = listOfStudents.Count();
        int first_index, last_index;

        for (first_index = 1; first_index < student_count; first_index++)
        {
            last_index = first_index - 1;
            Student first = listOfStudents[first_index];
            Student last = listOfStudents[last_index];

            if (asc){
                while (last_index >= 0 && DateTime.Compare(last.data, first.data) > 0)
                {
                    listOfStudents[last_index + 1] = listOfStudents[last_index];
                    last_index = last_index - 1;
                }
                listOfStudents[last_index + 1] = first;
            }
            else
            {
                while (last_index >= 0 && DateTime.Compare(last.data, first.data) < 0)
                {
                    listOfStudents[last_index + 1] = listOfStudents[last_index];
                    last_index = last_index - 1;
                }
                listOfStudents[last_index + 1] = first;
            }
        }
        return listOfStudents;
    }

如何解决这些问题？

Answer 1

您的第二个错误是因为您无法执行 obj.attribute，而 attribute 是带有属性名称的字符串。使用诸如 obj.GetType().GetProperty(propertyName).GetValue(obj, null) 之类的内容来按名称获取属性..

也许这会起作用，尝试一下，因为我目前没有您的学生数据或 C# 编译器来检查。评论它输出的内容。

public List<Student> insertion_Sort(List<Student> listOfStudents,ref String propertyName, Boolean asc)
    {
        Student obj = listOfStudents [0];
        int student_count = listOfStudents.Count();
        int first_index, last_index;
        dynamic prop= obj.GetType().GetProperty(propertyName);
        for (first_index = 1; first_index < student_count; first_index++)
        {
            last_index = first_index - 1;
            Student first = listOfStudents[first_index];
            Student last = listOfStudents[last_index];

            if (asc){
                while (last_index >= 0 && prop.GetValue(first, null)-prop.GetValue(last, null) > 0)
                {
                    listOfStudents[last_index + 1] = listOfStudents[last_index];
                    last_index = last_index - 1;
                }
                listOfStudents[last_index + 1] = first;
            }
            else
            {
                while (last_index >= 0 && prop.GetValue(first, null)-prop.GetValue(last, null) <0)
                {
                    listOfStudents[last_index + 1] = listOfStudents[last_index];
                    last_index = last_index - 1;
                }
                listOfStudents[last_index + 1] = first;
            }
        }
        return listOfStudents;
    }