使用.net 2.0进行分组是如何做到的

本文关键字：何做 net 使用 | 更新日期: 2023-09-27 18:02:49

正在做。net 2.0项目，没有linq，不能添加任何外部库。

构建一个我在实际项目中需要做的小示例。

如何按例如"员工"进行分组。

对于每一组我都需要做一些事情。

你如何在。net 2.0中分组?

     class Program
        {
            static void Main(string[] args)
            {
                List<Employee>employees=new List<Employee>();
                Employee employee = new Employee();
                employee.Id = 1;
                employee.Category = "Management";
                Employee employee2 = new Employee();
                employee.Id = 2;
                employee.Category = "Management";
                Employee employee3 = new Employee();
                employee.Id = 3;
                employee.Category = "Director";
                Employee employee4 = new Employee();
                employee.Id = 4;
                employee.Category = "Worker";
                Employee employee5= new Employee();
                employee.Id = 5;
                employee.Category = "Director";
                Employee employee6 = new Employee();
                employee.Id = 6;
                employee.Category = "Worker";
                employees.AddRange(new Employee[] { employee, employee2, employee3, employee4, employee5, employee6 });
                //1)Group them by category in .net 2.O NO LINQ
                //2)Foreach item in the group do something.
                Console.WriteLine("??");
            }
        }
        public class Employee
        {
            public int Id { get; set; }
            public string Name { get; set; }
            public string Category { get; set; }
        }

谢谢你的建议

使用.net 2.0进行分组是如何做到的

如何:

Dictionary<string, List<Employee>> groups =
       new Dictionary<string, List<Employee>>();
foreach(Employee emp in employees) {
    List<Employee> group;
    if(!groups.TryGetValue(emp.Category, out group)) {
        group = new List<Employee>();
        groups.Add(emp.Category, group);
    }
    group.Add(emp);
}
foreach(KeyValuePair<string,List<Employee>> pair in groups) {
    Console.WriteLine(pair.Key);
    foreach(Employee emp in pair.Value) {
        Console.WriteLine(emp.Id);
    }
}

您可以使用Dictionary<TKey,List<TValue>>。

foreach(var employee in employees)
{
  List<Employee> values;
  if(!dict.TryGetValue(employee.Category,out values))
  {
    values=new List<Employee>();
    dict.Add(employee.Category,values);
  }
  values.Add(employee);
}

您可以使用Dictionary<字符串，List>>

Dictionary<string, List<Employee>> dict = new Dictionary<string, List<Employee>>();
foreach(Employee e in employees)
{
    if(!dict.contains(e.Category))
        dict.Add(e.Category, new List<Employee()>);
    dict[e.Category].Add(e);
}

试试下面的代码。如果你想更改GroupBy，只需使用不同的GroupFieldDelegate。

    public delegate string GroupFieldDelegate(Employee e);
    private static string CategoryGrouping(Employee e)
    {
        return e.Category;
    }

    static Dictionary<string, List<Employee>> Group(List<Employee> Data, GroupFieldDelegate Grouping)
    {
        Dictionary<string, List<Employee>> result = new Dictionary<string, List<Employee>>();
        foreach (Employee e in Data)
        {
            string Category = Grouping(e);
            if (result.ContainsKey(Category)) result[Category].Add(e);
            else (result[Category] = new List<Employee>()).Add(e);c
        }
        return result;
    }
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