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How to delete an item from a generic list

Tags:

c#

list

generics

I have a generic list

How do I remove an item?

EX:

Class Student
{
    private number;
    public Number
    {
        get( return number;)
        set( number = value;)
    }

    private name;
    public Name
    {
        get( return name;)
        set( name = value;)
    }

    main()
    {
        static List<student> = new list<student>();

        list.remove...???
    }
}
like image 225
mah_85 Avatar asked Feb 04 '11 23:02

mah_85


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6 Answers

Well, there is nothing to remove because your list is empty (you also didn't give it an identifier, so your code won't compile). You can use the Remove(T item) or RemoveAt(int index) to remove an object or the object at a specified index respectively (once it actually contains something).

Contrived code sample:

void Main(...)
{
    var list = new List<Student>();
    Student s = new Student(...);
    list.Add(s);

    list.Remove(s); //removes 's' if it is in the list based on the result of the .Equals method

    list.RemoveAt(0); //removes the item at index 0, use the first example if possible/appropriate
}
like image 130
Ed S. Avatar answered Oct 05 '22 23:10

Ed S.



From your comments I conclude that you read student name from input and you need to remove student with given name.

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

    public Student (string name, int number)
    {
        Name = name;
        Number = number;
    }
}


var students = new List<Student> {
    new Student ("Daniel", 10),
    new Student ("Mike", 20),
    new Student ("Ashley", 42)
};

var nameToRemove = Console.ReadLine ();
students.RemoveAll (s => s.Name == nameToRemove); // remove by condition

Note that this will remove all students with given name.

If you need to remove the first student found by name, first use First method to find him, and then call Remove for the instance:

var firstMatch = students.First (s => s.Name == nameToRemove);
students.Remove (firstMatch);

If you want to ensure there is only one student with given name before removing him, use Single in a similar fashion:

var onlyMatch = students.Single (s => s.Name == nameToRemove);
students.Remove (onlyMatch);

Note that Single call fails if there is not exactly one item matching the predicate.

like image 32
Dan Abramov Avatar answered Oct 05 '22 23:10

Dan Abramov


List<Student> students = new List<Student>();
students.Add(new Student {StudentId = 1, StudentName = "Bob",});
students.RemoveAt(0); //Removes the 1st element, will crash if there are no entries

OR to remove a known Student.

//Find a Single Student in the List.
Student s = students.Where(s => s.StudentId == myStudentId).Single();
//Remove that student from the list.
students.Remove(s);
like image 26
DaveShaw Avatar answered Oct 06 '22 00:10

DaveShaw


Well, you didn't give your list a name, and some of your syntax is wonky.

void main()
{
   static List<Student> studentList = new List<Student>();
}

// later
void deleteFromStudents(Student studentToDelete)
{
   studentList.Remove(studentToDelete);
}

There are more remove functions detailed here: C# List Remove Methods

like image 20
Andrew Avatar answered Oct 06 '22 01:10

Andrew


int count=queue.Count;

        while(count>0)
        {
            HttpQueueItem item = queue[0];
            /// If post succeeded..
            if (snd.IsNotExceedsAcceptedLeadsPerDayLimit(item.DataSaleID, item.AcceptedLeadsPerDayLimit) && snd.PostRecord(item.DataSaleDetailID, item.PostString, item.duplicateCheckHours, item.Username, item.Password, item.successRegex))
            {
                if (item.WaitTime > 0)
                    Thread.Sleep(item.WaitTime);
                queue.Remove(item);
            }
                ///If Exceeds Accepted leads per day limit by DataSale..
            else if (!snd.IsNotExceedsAcceptedLeadsPerDayLimit(item.DataSaleID, item.AcceptedLeadsPerDayLimit))
            {
                queue.RemoveAll(obj => obj.DataSaleID == item.DataSaleID);
            }
                /// If Post failed..
            else //if (!snd.PostRecord(item.DataSaleDetailID, item.PostString, item.duplicateCheckHours, item.Username, item.Password, item.successRegex))
            {
                queue.Remove(item);
            }
            count = queue.Count;
        }
like image 37
user1737636 Avatar answered Oct 06 '22 01:10

user1737636


To delete a row or record from generic list in grid view, just write this code-

List<Address> people = new List<Address>();
Address t = new Address();
people.RemoveAt(e.RowIndex);
grdShow.EditIndex = -1;
grdShow.DataSource = people;
grdShow.DataBind();
like image 21
SBS Avatar answered Oct 06 '22 01:10

SBS