how to check that a list contains another list item in C#

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Hello,

How to find a string is already present in a list.For example i have a list that contains data now if i want to write the data in to another list during this i want to keep a condition whether the string is already present in the list.I am using the below code but its not working can you kindly help me

C#

List<list><string>> Messlist
List<string> val= new List<string>();

if (!(Messlist.Contains(val)))
{
---
}

Posted 31-Mar-15 0:03am

Rocky_Bas

Updated 31-Mar-15 0:14am

CHill60

v3

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4 solutions

Solution 3

Here is some good example for you.
Try this

http://www.dotnetperls.com/intersect[^]

http://stackoverflow.com/questions/7187996/intersect-two-list-in-c-sharp[^]

Posted 31-Mar-15 0:30am

King Fisher

Solution 4

try the below

List<string> newlist = Messlist.Distinct().ToList();

Thank You,
--RG

Posted 31-Mar-15 1:46am

Ramug10

Comments

CHill60 31-Mar-15 7:49am

How does this determine if an item, or a list of items, is already present in the list?

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Abhinav S · Accepted Answer · 2015-03-31T00:16:00

Solution 1

Try LINQ -

C#

var result = Messlist
    .Where(x=> x.Contains(searchString));

Posted 31-Mar-15 0:16am

Abhinav S

Comments

Sergey Alexandrovich Kryukov 31-Mar-15 7:34am

5ed.
—SA

Abhinav S 31-Mar-15 7:42am

Thank you SA.

CHill60 · Accepted Answer · 2015-03-31T00:20:00

Your problem is that val is another List but Contains expects a string

To see if one list contains the values in another use the List<t>.Intersect[^] method and check against the ~~Count~~ Any property

E.g.

C#

private void button1_Click(object sender, EventArgs e)
{
    var l1 = new List<string> {"1", "2", "3", "4", "5", "6"};
    var l2 = new List<string> { "4", "5"};
    var l3 = new List<string> {"7", "8"};

    ListCheck(l1, l2);
    ListCheck(l1, l3);
}

private static bool ListCheck<T>(IEnumerable<T> l1, IEnumerable<T> l2)
{
    // TODO: Null parm checks
    if (l1.Intersect(l2).Any())
    {
        Console.WriteLine("matched");
        return true;
    }
    else
    {
        Console.WriteLine("not matched");
        return false;
    }
}

Or change val to be a single string