List.ToDictionary可以简单的将List转换为Dictionary，非常方便。如果需要从数据库加载表，在程序中大量查表的应用场景，这个操作拥有较高的效率。
看示例：
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public class Student { public int GradeId { get; set; } public int ClassId { get; set; } public int Sequence { get; set; } public string Name { get; set; } } |
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List<Student> students = new List<Student>(); students.Add(new Student { GradeId = 1, ClassId = 1, Sequence = 1, Name = "张三", }); students.Add(new Student { GradeId = 1, ClassId = 1, Sequence = 2, Name = "李四", }); students.Add(new Student { GradeId = 2, ClassId = 1, Sequence = 1, Name = "王五", }); //ToDictionary(key构造,value构造) Dictionary<string,string> dictStudents = students.ToDictionary( x => x.GradeId.ToString()+"-"+x.ClassId.ToString()+"-"+x.Sequence.ToString(), x => x.Name); //得到“王五” var student2_1_name = dictStudents["2-1-1"]; |
