How can I use contains and indexof?

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if drank.contains doenst seem to work. can someone help me with that?

What I have tried:

public partial class Form1 : Form
    {

        administration admin = new administration();
        //reserveer Reserveer = new reserveer();
        public Form1()
        {
            InitializeComponent();

            load();
        }


        public void load()
        {
            List<groep> Groepnaam = admin.groepsnaam();
            List<persoon> personen = admin.spelers();
            
            foreach (Groep naam in Groepnaam)
            {
                listBox3.Items.Add(naam.Groepsnaam );

            }
            foreach (persoon Persoon in personen)
            {
                listBox1.Items.Add(Persoon);
            }
        }
        

        
        private void button1_Click(object sender, EventArgs e)
        {
            int aantalstrikes = Convert.ToInt32(numstrikes.Value);
            int aantalspares = Convert.ToInt32(numspares.Value);
            int aantalpunten = Convert.ToInt32(tbpunten.Text);
            int aantalbier = Convert.ToInt32(aantbier.Text);
            int prijs = 2;
            

            admin.voegtoebier(aantalbier, prijs);
            
            admin.voegtoescore(aantalpunten, aantalstrikes, aantalspares);
            List<score> Punten = admin.punten();
            
            foreach (score punt in Punten)
            {
                listBox2.Items.Add(punt);
                


            }
            List<bier> consumptie = admin.Bier();
            
            foreach(bier drank in consumptie)
            {
                listBox4.Items.Add(drank);
                


            }
              if (drank.contains)
            {


             }




        }

Posted 4-Jan-18 5:16am

Member 13554627

Updated 4-Jan-18 5:17am

v2

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Comments

David_Wimbley 4-Jan-18 11:36am

Your code isn't terribly clear as you are doing .contains (should be .Contains) on a variable that is used within a foreach loop...but you are accessing it outside of your foreach loop.

Regardless, I think you might want to look at using .Any(.

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OriginalGriff · Accepted Answer · 2018-01-04T05:44:00

First off, drank is out of scope by the time your code gets to the end of the foreach loop - so no matter what it was, you can't use it - it no longer exists.

Secondly, Contains and IndexOf require a class that implements IEnumerable<T> so unless the bier class is actually a derived from a List or similar, or you added a Contains method to it yourself, you can't call it. And from the code above that, I don't think it is.
This is what you are trying to do, I think:

C#

public class Beer
    {
    public string Name { get; set; }
    public int Abv { get; set; }
    }
private void MyButton_Click(object sender, EventArgs e)
    {
    List<Beer> beers = new List<Beer>();
    Beer a = new Beer() { Name = "Shimptons Old Cleanser", Abv = 17 };
    beers.Add(a);
    Beer b = new Beer() { Name = "Horse Urine", Abv = 3 };
    beers.Add(b);
    Beer c = new Beer() { Name = "Heinekon", Abv = 1 };
    beers.Add(c);
    if (beers.Contains(b))
        {
        Console.WriteLine("Yes, {0} is a beer. Technically.", b.Name);
        }
    Console.WriteLine("{0} is at index {1}", c.Name, beers.IndexOf(c));
...

Quote:</div>well sort off, i want to check a value (int) that comes from a sql database. but where can i use the contain method to check if there is an number for example 100 in my database.

Basically, don't.

If you want to know if something exists in a DB, ask the DB!

SQL

SELECT COUNT(*) FROM MyTable WHERE MyColumn = 100

Use that with ExecuteScalar, and it will return the number of items with that value.

If you have built them into a collection of bier objects, then use the Linq Exists method instead:

C#

if (beers.Exists(x => x.Abv = 3))
    {
    Console.WriteLine("Yes, {0} is a beer. Technically.", b.Name);
    }

The Contains method only looks for an exact match on an object reference to an object reference in the collection, it can't look at the object internals.