C# List、Array、Dictionary之间相互转换

• Array转换为List
• List转换为Array
• Array转Dictionary
• Dictionary转Array
• List转Dictionary
• Dictionary转List

• IQueryable,IEnumerable,List相互转换

  基本资料, 定义Student类，并添加属性

class Student 
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Gender { get; set; }
}
//创建数组
Student[] StudentArray = new Student[3];
StudentArray[0] = new Student()
{
    Id = 12,
    Name = "Lucky",
    Gender = "Male"
};
StudentArray[1] = new Student()
{
    Id = 23,
    Name = "Poppy",
    Gender = "Male"
};
StudentArray[2] = new Student()
{
    Id = 55,
    Name = "Jack",
    Gender = "Female"
};

---

1. Array转换为List

List StudentList = StudentArray.ToList();
foreach (Student student in StudentList)
{
    Console.WriteLine("Id = " + student.Id + " " + " Name = " + student.Name + " " + " Gender = " + student.Gender);
}

2. List转换为Array

Student[] ListToArray = StudentList.ToArray();
foreach (Student student in ListToArray)
{
    Console.WriteLine("Id = " + student.Id + " " + " Name = " + student.Name + " " + " Gender = " + student.Gender);
}

3. Array转Dictionary

Dictionary StudentDictionary = studentArray.ToDictionary(key=>key.Id, Studentobj => Studentobj);
foreach (KeyValuePair student in StudentDictionary)
{
    Console.WriteLine("Id = " + student.Key + " " + " Name = " + student.Value.Name + " " + " Gender = " + student.Value.Gender);
}

4. Dictionary转Array

Student[] DictionaryToArray = StudentDictionary.Values.ToArray();
foreach (Student student in DictionaryToArray)
{
    Console.WriteLine("Id = " + student.Id + " " + " Name = " + student.Name + " " + " Gender = " + student.Gender);
}

5. List转Dictionary

Dictionary ListToDictionary = ListToArray.ToDictionary(key => key.Id, value => value);
foreach (KeyValuePair student in ListToDictionary)
{
    Console.WriteLine("Id = " + student.Key + " " + " Name = " + student.Value.Name + " " + " Gender = " + student.Value.Gender);
}

6. Dictionary转List

List DictionaryToList = StudentDictionary.Values.ToList();
foreach (Student student in DictionaryToList)
{
    Console.WriteLine("Id = " + student.Id + " " + " Name = " + student.Name + " " + " Gender = " + student.Gender);
}

IQueryable,IEnumerable都可以通过ToList()转换为类型。

PassUser.ToList();

如果需要反向转换，有两个很好用的方法AsQueryable()，AsEnumerable(),可以顺利将List转换为IQueryable,IEnumerable。

List ListUser = new List();
PassUser = ListUser.AsQueryable();