update a generic List Item using C#

Question

I could not figure it out how to update an item of a generic list after review all the questions posted here, I'm sorry for that. Here is my question:

I have this structure:

List<LineInfo> Lines = new List<LineInfo>();
    LineInfo LInfo;
    struct LineInfo
    {
        public int line;
        public int WO;
        public string Brand;
        public string Model;
        public string Customer;
        public int Qty;
        public int Target;
        public string Leader;
        public string Start;
        public string End;
        public int Percent;
    }

And I want to update the field "Percent" of one of the LInfo items entered, I have the current position (aCurrentLine).

LInfo.Percent = Convert.ToInt32((RealProduced / DesireProd) * 100);                 
Lines[aCurrentLine]....?

Please advise, thanks.

Jon Skeet · Accepted Answer · 2011-08-17 14:10:20Z

3

Just

LInfo.Percent = Convert.ToInt32((RealProduced / DesireProd) * 100);
Lines[aCurrentLine] = LInfo;

should work... but please don't use either public fields or mutable structs. Both are terrible in terms of maintainability and unintended effects.

Most of the types you create in C# are likely to be classes - it's relatively rare that you'll want to create a value type (struct). You should make sure you're aware of the differences between the two.

Likewise fields in C# should almost always be private. They should be an implementation detail of the type, not part of its public API. Use properties instead - automatically-implemented properties in C# 3 make these almost as compact to write as fields, if you just want a trivial property.

answered Aug 17, 2011 at 14:10

Jon Skeet

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1 Comment

Somebody Over a year ago

Awesome! thank you, and regarding mutable structs, I need to read about it ;)

Ashley John · Accepted Answer · 2011-08-17 14:11:18Z

1

I have just one adivice .Mutable stuctures are evil. Try to avoid it .

Lines[aCurrentLine] = LInfo;

you wont be able to access Lines[aCurrentLine].Percent as it updates just a temporary copy.

answered Aug 17, 2011 at 14:11

Ashley John

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Comments

SBS · Accepted Answer · 2012-12-13 08:40:45Z

for update a generic list record with grid view.just put this code.

 List<Address> people = (List<Address>)Session["People"];
        people[e.RowIndex].DoorNo = ((TextBox)grdShow.Rows[e.RowIndex].Cells[2].Controls[0]).Text;
        people[e.RowIndex].StreetName = ((TextBox)grdShow.Rows[e.RowIndex].Cells[3].Controls[0]).Text;
        people[e.RowIndex].City = ((TextBox)grdShow.Rows[e.RowIndex].Cells[4].Controls[0]).Text;
        people[e.RowIndex].PhoneNo = ((TextBox)grdShow.Rows[e.RowIndex].Cells[5].Controls[0]).Text;
        grdShow.EditIndex = -1;
        grdShow.DataSource = people;
        grdShow.DataBind();

and put this code to page load event.

if (!IsPostBack)
        {

            List<Address> people = new List<Address>();
            Session["People"] = people;
        }

for create generic list using grid view write this code on the button event(it take the data from text boxes and save in the list)

GenerateList();//call the method GenerateList();

the sytex of GenerateList();

private void GenerateList()
    {
        if (Session["People"] != null)
        {

            List<Address> people = (List<Address>)Session["People"];

            Address a1 = new Address();

            a1.DoorNo = txtDoorno.Text;
            a1.StreetName = txtStreetName.Text;
            a1.City = txtCityname.Text;
            a1.PhoneNo = txtPhoneno.Text;
            people.Add(a1);
            Session["People"] = people;
            grdShow.DataSource = people;
            grdShow.DataBind();
        }
    }

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