removing similar string from an array in c#

Question

Suppose i have array of strings as follows:

string[] array = new string[6];

array[0] = "http://www.s8wministries.org/general.php?id=35";
array[1] = "http://www.s8wministries.org/general.php?id=52";
array[2] = "http://www.ecogybiofuels.com/general.php?id=6";
array[3] = "http://www.stjohnsheriff.com/general.php?id=186";
array[4] = "http://www.stjohnsheriff.com/general.php?id=7";
array[5] = "http://www.bickellawfirm.com/general.php?id=1048";

Now I want to store only one similar occurrence of the string ie http://www.s8wministries.org/general.php?id=35 discarding any other string that has http://www.s8wministries.org and store it in another array.

Please how do I go about this?

my attempt is as follows:-

//remove similar string from array storing only one similar in another array

        foreach (var olu in array)
        {

            string findThisString = olu.ToString();
            string firstTen = findThisString.Substring(0, 15); 

            // See if substring is in the table.
            int index1 = Array.IndexOf(array, firstTen);  //substring is not in table

        }

Answer 1

Here is how I would approach this

1. Initialize a hashtable or a dictionary for holding domain names
2. Loop through each item
3. Do a string split operation with using '', '.', '/' etc as delimiters - find out the domain by parsing the parts.
4. Check if the domain name exists in the hashtable. If it does, discard the current entry. If it doesn't exist, insert into the hashtable and also add the current entry to a new list of your selected entries.

Another option would be to sort the entries alphabetically. Go through them one at a time. Select an entry with the domain name. Skip all the next entries with the same domain name. Select the next entry when the domain name changes again.

Answer 2

Let's say the result is to be stored in an array called unique_array and that your current array is called array. Pseudo-code follows:

bool found = false;
for(int i = 0; i < array_size; i++)
{   if(array[i] starts with "http://www.s8wministries.org")
    {   if(found) continue;
        found = true;
    }
    add array[i] to end of unique_array;
}

Answer 3

try this with List of string, so you have list of string containing URL, you can use URI class to compare domains:

for(int i = 0; i < strList.Length; i++)
{   
  Uri uriToCompare = new Uri(strArray[i]);
  for(int j = i+1; j < strArray.Length; j++){
     Uri uri = new Uri(strArray[j]);
     if( uriToCompare.Host  == uri.Host){
        strList.RemoveAt(j);
     }     
  }
}

Answer 4

I would go the way of slightly more automation by creating a class that inherits IEqualityComparer (utilizing the great answer to this question):

public class PropertyComparer<T> : IEqualityComparer<T>
{
    Func<T, T, bool> comparer;

    public PropertyComparer<T>(Func<T, T, bool> comparer)
    {
        this.comparer = comparer;
    }

    public bool Equals(T a, T b)
    {
        return comparer(a, b);
    }

    public int GetHashCode(T a)
    {
        return a.GetHashCode();
    }
}

Once you have that class - you can use Distinct like this:

var distinctArray = array.Select(s => new Uri(s)).Distinct(new PropertyComparer<Uri>((a, b) => a.Host == b.Host));

That leaves you with an array only containing distinct domains. It's an IEnumerable so you may want to .ToList() it or something, or revert it back to strings from Uris . But I think this method makes for much more readable code.

Answer 5

Please try below Code:

    string[] array = new string[6];
    array[0] = "http://www.s8wministries.org/general.php?id=35";
    array[1] = "http://www.s8wministries.org/general.php?id=52";
    array[2] = "http://www.ecogybiofuels.com/general.php?id=6";
    array[3] = "http://www.stjohnsheriff.com/general.php?id=186";
    array[4] = "http://www.stjohnsheriff.com/general.php?id=7";
    array[5] = "http://www.bickellawfirm.com/general.php?id=1048";
    var regex = @"http://www.[\w]+.[\w]+";
    var distList = new List<string>();
    var finalList = new List<string>();
    foreach (string str in array)
    {
        Match match = Regex.Match(str, regex, RegexOptions.IgnoreCase);
        if (match.Success)
        {
            var uniqueUrl = match.Groups[0].Value;
            if (!distList.Contains(uniqueUrl))
            {
                distList.Add(uniqueUrl);
                finalList.Add(str);
            }
        }
    }

Here finalList contains the required list of URLs