Check if List contains incremental Id using C# and VB.Net in ASP.Net

Hi venkatg,

Check this example. Now please take its reference and correct your code.

Code

C#

protected void Page_Load(object sender, EventArgs e)
{
    var students = new List<Student>()
    {
        new Student() { Id = 1, Name = "Bill" },
        new Student() { Id = 4, Name = "Steve" },
        new Student() { Id = 5, Name = "Ram" },
        new Student() { Id = 4, Name = "Abdul" }
    };
    students = students.OrderBy(x => x.Id).ToList();

    bool isInOrder = true;
    int id = 0;
    int newId = 0;
    for (int i = 0; i < students.Count; i++)
    {
        id = students[i].Id;
        if (i == 0)
        {
            newId = id + 1;
        }
        else
        {
            if (id != newId)
            {
                isInOrder = false;
                break;
            }
            newId = id + 1;
        }
    }

    if (isInOrder)
    {
        ClientScript.RegisterClientScriptBlock(this.GetType(), "", "alert('ID is in incremntal order.')", true);
    }
    else
    {
        ClientScript.RegisterClientScriptBlock(this.GetType(), "", "alert('ID is not in incremntal order.')", true);
    }
}

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
}

VB.Net

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs) Handles Me.Load
    Dim students = New List(Of Student)() From {
        New Student() With {.Id = 1, .Name = "Bill"},
        New Student() With {.Id = 4, .Name = "Steve"},
        New Student() With {.Id = 5, .Name = "Ram"},
        New Student() With {.Id = 4, .Name = "Abdul"}
    }
    students = students.OrderBy(Function(x) x.Id).ToList()
    Dim isInOrder As Boolean = True
    Dim id As Integer = 0
    Dim newId As Integer = 0
    For i As Integer = 0 To students.Count - 1
        id = students(i).Id
        If i = 0 Then
            newId = id + 1
        Else
            If id <> newId Then
                isInOrder = False
                Exit For
            End If
            newId = id + 1
        End If
    Next
    If isInOrder Then
        ClientScript.RegisterClientScriptBlock(Me.GetType(), "", "alert('ID is in incremntal order.')", True)
    Else
        ClientScript.RegisterClientScriptBlock(Me.GetType(), "", "alert('ID is not in incremntal order.')", True)
    End If
End Sub

Public Class Student
    Public Property Id As Integer
    Public Property Name As String
End Class