Adding to list with foreach loop

Question

I am currently trying to add objects(students). I am creating in a foreach loop to an object list made up of students, each list object ends up referencing to the same location and therefore the information on each list object is the same as the last student object created when the loop ends. The only information I have been able to find for adding an object to a list using a foreach loop states to create a new instance of the object which I thought I was doing with the Student stud = new Student line.

I have also tried using the default constructor and using properties instead of arguments, then adding the student to the list however I receive the same result.

Any help in adding objects to an object list with a foreach loop would be greatly appreciated.

foreach loop:

foreach (DataRow datrow in dt.Rows)
{
    Student stud = new Student(
        datrow["ID"].ToString(),
        datrow["fName"].ToString(),
        datrow["lName"].ToString(),
        datrow["GPA"].ToString(),
        datrow["Graduate"].ToString()
    );
    studentList.Add(stud);
}

My Student Constructor:

public Student(
    string studentID,
    string fName,
    string lName,
    string studentGPA,
    string graduate)
{
    iD = studentID;
    firstName = fName;
    lastName = lName;
    gPA = studentGPA;
    grad = graduate;
}

statement used to fill dt

                OleDbCommand cmd = new OleDbCommand(strSql, con);
                con.Open();
                cmd.CommandType = CommandType.Text;
                OleDbDataAdapter dc = new OleDbDataAdapter(cmd);
                dc.Fill(ds, "ID");
                dt = ds.Tables["ID"];
                const char DELIM = ',';
                foreach (DataRow datrow in dt.Rows)

"this" information that each object refers to and is re-written for every new object

Result

whats wrong with the results? My screen is to small for me to make heads or tails of the picture. — Jacobr365
– Jacobr365, Commented Nov 16, 2016 at 14:58
This code looks correct. How have you determined that the problem is here and not somewhere else? — David
– David, Commented Nov 16, 2016 at 14:58
Also, in the first screen shot, how can values for this already be populated when you're paused on the first line of the constructor? That seems strange. — David
– David, Commented Nov 16, 2016 at 14:59
Did you check that the rows do not all contain same information? One way to determine if the objects in the list are really all the same or just have same values is to right click and select "generate object id". If they all the same object, they should all get the same id — Mats391
– Mats391, Commented Nov 16, 2016 at 15:01
Max, please include the statement or query that is used to fill the dt object (e.g. Linq or SQL). If all objects contain the same data then probably the rows do too. — Peter B
– Peter B, Commented Nov 16, 2016 at 15:03

pinkfloydx33 · Accepted Answer · 2016-11-16 15:33:49Z

2

Your private variables are most likely static. This would explain why the variables already have a value in the constructor (which they wouldn't for normal instance variables). The static values are being returned by your properties (which explains how they have values already as well). Change your variables to instance (not static)

answered Nov 16, 2016 at 15:33

pinkfloydx33

12.9k3 gold badges54 silver badges70 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Sir Rufo Over a year ago

Nice crystal ball :o)

Karthik Elumalai · Accepted Answer · 2016-11-16 15:23:46Z

2

Hi my suggestion is just try by declaring class variable outside like this, see whether its works

Student stud;

    foreach (DataRow datrow in dt.Rows)
    {
            stud = new Student(
            datrow["ID"].ToString(),
            datrow["fName"].ToString(),
            datrow["lName"].ToString(),
            datrow["GPA"].ToString(),
            datrow["Graduate"].ToString()
        );
        studentList.Add(stud);
    }

please let me know your suggestions.

thanks karthik

answered Nov 16, 2016 at 15:23

Karthik Elumalai

1,6121 gold badge13 silver badges12 bronze badges

Collectives™ on Stack Overflow

Adding to list with foreach loop

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related