如何使用linq返回一个数组中与另一个数组的整数属性不匹配的整数?

所以,我的理解是,您希望获取PrimaryKeyDataV1的所有实例,这些实例的ServerID属性在linkedStudents参数的students.StudentID属性中都不存在?

internal static PrimaryKeyDataV1[] GetStudentsThatAreNotLinked(PrimaryKeyDataV1[] existingStudents, IQueryable<Student> linkedStudents)
{
    var results = existingStudents.Select(s => s.ServerID)
        .Except(linkedStudents.Select(link => link.StudentID))
        .ToArray();

    return existingStudents.Where(stud => results.Contains(stud.ServerID));
}

internal static int[] GetStudentIDsThatAreNotLinked(PrimaryKeyDataV1[] existingStudents, IQueryable<Student> linkedStudents)
{
    return existingStudents.Select(s => s.ServerID)
        .Except(linkedStudents.Select(link => link.StudentID))
        .ToArray();
}

如果您只需要返回ID,则可以使用以下方法:

existingStudents.Select(es => es.StudentID)
              .Except(linkedStudents.Select(ls => ls.ServerID));

你可以用查询理解的形式写这个,但我觉得不太清楚:

var result = (from es in existingStudents select es.StudentID);
             .Except
             (from ls in linkedStudents select ls.ServerID)

如果需要以数组形式返回结果,只需使用 .ToArray() 分机:

existingStudents.Select(es => es.StudentID)
              .Except(linkedStudents.Select(ls => ls.ServerID)).ToArray();

如果只需要返回id中的设置差异,则不需要创建自己的相等比较器。

    List<student> ExistingStudents = new List<student>();
    List<student> LinkedStudents = new List<student>();

    ExistingStudents.Add(new student {id=1, name="joe"});
    ExistingStudents.Add(new student { id = 2, name = "beth" });
    ExistingStudents.Add(new student { id = 3, name = "sam" });

    LinkedStudents.Add(new student { id = 2, name = "beth" });


    var students = from stud in ExistingStudents
                    where !(LinkedStudents.Select(x => x.id).Contains(stud.id))
                    select stud;

    foreach(student s in students)
    {
        System.Diagnostics.Debug.WriteLine(string.Format("id: {0}, name: {1}", s.id, s.name));
    }

public class student
{
    public int id;
    public string name;
}