Linq 等式运算符：SequenceEqual

检查元素的数量，每个元素的值及两个集合中元素的顺序是否相等,3个方面都相等则为true,否则为false

IList<string> strList1 = new List<string>(){"One", "Two", "Three", "Four", "Three"};
 
IList<string> strList2 = new List<string>(){"One", "Two", "Three", "Four", "Three"};
 
bool isEqual = strList1.SequenceEqual(strList2); // returns true

IList<string> strList1 = new List<string>(){"One", "Two", "Three", "Four", "Three"};
 
IList<string> strList2 = new List<string>(){ "Two", "One", "Three", "Four", "Three"};
 
bool isEqual = strList1.SequenceEqual(strList2); // returns false

//如果是引用类型,则比较的是引用
Student std = new Student() { StudentID = 1, StudentName = "Bill" };
 
IList<Student> studentList1 = new List<Student>(){ std };
 
IList<Student> studentList2 = new List<Student>(){ std };
        
bool isEqual = studentList1.SequenceEqual(studentList2); // returns true
 
Student std1 = new Student() { StudentID = 1, StudentName = "Bill" };
Student std2 = new Student() { StudentID = 1, StudentName = "Bill" };
 
IList<Student> studentList3 = new List<Student>(){ std1};
 
IList<Student> studentList4 = new List<Student>(){ std2 };
        
isEqual = studentList3.SequenceEqual(studentList4);// returns false

//在上面的示例中，studentList1和studentList2包含相同的学生对象std。 所以studentList1.SequenceEqual（studentList2）返回true。 但是，stdList1和stdList2包含两个独立的学生对象std1和std2。 
//所以现在，stdList1.SequenceEqual（stdList2）将返回false.

//要比较复杂类型的两个集合的值，您需要实现IEqualityComperar <T>接口，如下所示

class StudentComparer : IEqualityComparer<Student>
{
    public bool Equals(Student x, Student y)
    {
        if (x.StudentID == y.StudentID && x.StudentName.ToLower() == y.StudentName.ToLower())
            return true;
 
        return false;
    }
 
    public int GetHashCode(Student obj)
    {
        return obj.GetHashCode();
    }
}

// following returns true
bool isEqual = studentList1.SequenceEqual(studentList2, new StudentComparer());