C# List.Select()

List.Select()：一般List中的元素是对象的时候，可以通过Selec()获取列表中对象的属性值列表。

  1 using System.Collections;
  2 using System.Collections.Generic;
  3 using System.Linq;
  4 using UnityEngine;
  5 
  6 public class Test : MonoBehaviour
  7 {
  8     /// <summary>
  9     /// 所有学生
 10     /// </summary>
 11     public List<Student> students = new List<Student>();
 12 
 13     private void Start()
 14     {
 15         //提取所有学生的姓名和性别
 16         foreach (var nameAndGender in ExtractAllStudentNameAndAge())
 17         {
 18             Debug.Log(nameAndGender.name +"，" + nameAndGender.gender);
 19         }
 20 
 21         //提取所有学生的学号
 22         foreach (var id in ExtractAllStudentId())
 23         {
 24             Debug.Log(id);
 25         }
 26 
 27         //每个学生年龄是否大于23
 28         foreach (var item in AgeOver23())
 29         {
 30             Debug.Log(item);
 31         }
 32     }
 33 
 34     #region 提取所有学生的姓名和性别
 35 
 36     /*//写法1
 37     List<dynamic> ExtractAllStudentNameAndAge()
 38     {
 39         List<dynamic> allId = students.Select(
 40                t => (dynamic)new { t.name, t.gender }
 41                ).ToList();
 42 
 43         return allId;
 44     }*/
 45 
 46     //写法2
 47     List<NameAndGender> ExtractAllStudentNameAndAge()
 48     {
 49         List<NameAndGender> allId = students.Select(
 50                t => new NameAndGender(t.name, t.gender)
 51                ).ToList();
 52 
 53         return allId;
 54     }
 55     #endregion
 56 
 57     #region 提取所有学生的学号
 58 
 59     /*//写法1
 60     List<dynamic> ExtractAllStudentId()
 61     {
 62         List<dynamic> allId = students.Select(
 63                 t => (dynamic)t.id
 64                 ).ToList();
 65 
 66         return allId;
 67     }*/
 68 
 69     //写法2
 70     List<int> ExtractAllStudentId()
 71     {
 72         List<int> allId = students.Select(
 73                t => (int)t.id
 74                ).ToList();
 75 
 76         return allId;
 77     }
 78     #endregion
 79 
 80     #region 每个学生年龄是否大于23
 81 
 82     /*//写法1
 83     List<dynamic> AgeOver23()
 84     {
 85         List<dynamic> allResult = students.Select(
 86                t => (dynamic)t.age > 23
 87                ).ToList();
 88 
 89         return allResult;
 90     }*/
 91 
 92     //写法2
 93     List<bool> AgeOver23()
 94     {
 95         List<bool> allResult = students.Select(
 96                t => t.age > 23
 97                ).ToList();
 98 
 99         return allResult;
100     }
101     #endregion
102 }
103 /// <summary>
104 /// 学生信息
105 /// </summary>
106 [System.Serializable]
107 public class Student
108 {
109     /// <summary>
110     /// 名字
111     /// </summary>
112     public string name;
113     /// <summary>
114     /// 年龄
115     /// </summary>
116     public int age;
117     /// <summary>
118     /// 学号
119     /// </summary>
120     public int id;
121     /// <summary>
122     /// 性别
123     /// </summary>
124     public Gender gender;
125 
126     public override string ToString()
127     {
128         return string.Format("{0}，{1}，{2}，{3}", name, age, id, gender == Gender.Female ? "女" : "男");
129     }
130 }
131 /// <summary>
132 /// 性别
133 /// </summary>
134 public enum Gender
135 {
136     /// <summary>
137     /// 女性
138     /// </summary>
139     Female,
140     /// <summary>
141     /// 男性
142     /// </summary>
143     Male,
144 }
145 public class NameAndGender
146 {
147     /// <summary>
148     /// 名字
149     /// </summary>
150     public string name;
151     /// <summary>
152     /// 性别
153     /// </summary>
154     public Gender gender;
155     public NameAndGender(string name, Gender gender)
156     {
157         this.name = name;
158         this.gender = gender;
159     }
160     public override string ToString()
161     {
162         return string.Format("{0}，{1}", name, gender == Gender.Female ? "女" : "男");
163     }
164 }