return a list of objects in c#

Question

i need to build a list in a function, then return it to a another list variable the problem is: inside the function the list is built properly but when i return it to the outer variable it seems like all the elements of the outer list are all similar to the last one added to it inside the function. what is the reason of this?

this is my code:

List<stu> fillObject(SqlDataReader rd)
    {
        List<stu> stList = new List<stu>();
        stu stObj = new stu();
        while (rd.Read())
        {
            stObj.username = rd["username"].ToString();
            stObj.password = rd["password"].ToString();
            stObj.fname = rd["fname"].ToString();
            stObj.lname = rd["lname"].ToString();
            stObj.faculty = rd["faculty"].ToString();
            stList.Add(stObj);

        }
        return stList;
    }

here is the call of the function:

var friendsList = fillObject(rd);

so looping though 'friendList' would give the same last object added in the builder function.

yogi · Accepted Answer · 2014-07-05 06:03:31Z

1

Try this

List<stu> fillObject(SqlDataReader rd)
    {
        List<stu> stList = new List<stu>();

        while (rd.Read())
        {
            stu stObj = new stu();
            stObj.username = rd["username"].ToString();
            stObj.password = rd["password"].ToString();
            stObj.fname = rd["fname"].ToString();
            stObj.lname = rd["lname"].ToString();
            stObj.faculty = rd["faculty"].ToString();
            stList.Add(stObj);

        }
        return stList;
    }

what you were missing is initializing stu inside while, due to which there was only one stu object that is being added again and again into stList.

answered Jul 5, 2014 at 6:03

yogi

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Comments

Dani · Accepted Answer · 2014-07-05 06:02:19Z

0

You need to create New STU object inside the loop, Otherwise you keep changing the same referenced object.

answered Jul 5, 2014 at 6:02

Dani

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1 Comment

user3674184 Over a year ago

i need x-y, but i don't know who is bigger is there a max(x,y)-min(x,y) in C#?

Pawan · Accepted Answer · 2014-07-05 06:04:18Z

0

Try This :

List<stu> fillObject(SqlDataReader rd)
{
    List<stu> stList = new List<stu>();
    //stu stObj = new stu();
    while (rd.Read())
    {

       stList.Add(new stu 
       {
        username = rd["username"].ToString(),
        password = rd["password"].ToString(),
        fname = rd["fname"].ToString(),
        lname = rd["lname"].ToString(),
        faculty = rd["faculty"].ToString()

      });

    }
    return stList;
}

answered Jul 5, 2014 at 6:04

Pawan

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2 Comments

user3674184 Over a year ago

do you really mean: stObj.Add() ?

Pawan Over a year ago

there is no need to create stu class object inside loop.

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