Question

On the click of the button I’m writing this:

 protected void Button1_Click(object sender, EventArgs e)
    {
        List<Students> student = new List<Students>()
        {
            new Students {FirstName= "Ram", LastName= "Gol"},
            new Students {FirstName= "Ran", LastName= "Gom"},
            new Students {FirstName= "Rao", LastName= "Gon"},
            new Students {FirstName= "Rap", LastName= "Goo"}
        };

        IEnumerable<Students> empQuery = from s in student
                       where s.FirstName.Length ==3
                       select s.FirstName;
        foreach (var stud in empQuery)
        {
            Button1.Text = stud;
        }

And I’m using System.Collection.Generic also. But I’m getting error of

the type or namespace name ‘Students’ could not be found (are you
missing a using directive or an assembly reference?)

Please let me know what I’m doing wrong.

Answer 1

1. If the Class is defined in the current project skip to step 4.
2. Make sure that the assembly where Students is defined is in the projects reference folder (or that if it exsits that it is not a broken reference). If it is not there then add it.
3. If the reference is invalid, delete and re-add it by either pulling in a project reference or browsing to the location of the assembly. It will most likely be in the projects section of add reference.
4. If the reference is valid, put a Using directive which specifies the Students namespace so it can be used.