Check if a list<StringCollection> contains list<string>

Question

Given a list<StringCollection> how do most efficiently check whether all string are contained in any of the StringCollection s?

Example:

using System;
using System.Collections.Specialized;
using System.Collections.Generic;
                    
public class Program
{
    public static void Main()
    {
        // Create and initializes a new StringCollection.
        StringCollection myCol0 = new StringCollection();
        StringCollection myCol1 = new StringCollection();
        StringCollection myCol2 = new StringCollection();

        StringCollection SearchCol = new StringCollection();

        // Add a range of elements from an array to the end of the StringCollection.
        String[] myArr0 = new String[] { "RED", "car", "boat" };
        myCol0.AddRange( myArr0 );
        
        // Add a range of elements from an array to the end of the StringCollection.
        String[] myArr1 = new String[] { "Blue", "Goku", "Nappa" };
        myCol1.AddRange( myArr1 );
        
        // Add a range of elements from an array to the end of the StringCollection.
        String[] myArr2 = new String[] { "Yellow", "Winter", "Summer" };
        myCol2.AddRange( myArr2 );
        
        // Add a range of elements from an array to the end of the StringCollection.
        String[] myArr3 = new String[] { "Yellow", "Blue", "RED" };
        SearchCol.AddRange( myArr3 );
        
        List<StringCollection> a = new List<StringCollection>();
        a.Add(myCol0);
        a.Add(myCol1);
        a.Add(myCol2);
    }
}

In this case I want to know whether the strings in SearchCol is contained within the stringcollections stored in List<StringCollection> a

In this case I just like to know which of the searchCol strings is not included in the List<StringCollection> a

The only way I see this it possible to do so is via a double for loop? Is there any datastructure that would be more efficient rather than an stringcollection?

Answer 1

Is there any datastructure that would be more efficient rather than an stringcollection

Efficient in what way? Of course you should normally use a IEnumerable<string> (like a string[] vor List<string> ) since StringCollection is not generic.

But you can also use StringCollection , you have to cast each item from object to string:

var allStrings = a.SelectMany(c => c.Cast<string>());
var searchStrings = SearchCol.Cast<string>();
bool allSearchStringsAreContained = searchStrings.All(allStrings.Contains);

as for the "how do most efficiently", this simple approach is efficient, but if you have a large list of strings that you search or huge string lists, you could use a set based approach:

HashSet<string> set = new HashSet<string>(searchStrings);
bool allSearchStringsAreContained = set.IsSubsetOf(allStrings);

Finally, if you want to ignore the case, so treat "RED" and "Red" same:

Approach 1:

bool allSearchStringsAreContained = searchStrings.All(s => allStrings.Contains(s, StringComparer.OrdinalIgnoreCase));

Approach 2:

HashSet<string> set = new HashSet<string>(searchStrings, StringComparer.OrdinalIgnoreCase);