Traverse a list and retrieve a specified value from List<> in asp.net/c#

I have a list which is defined as

   List<SoftwareTitles> softwareTitlesList = new List<SoftwareTitles>();

and the SoftwareTitles is a class which is defines as follows:

public class SoftwareTitles
{
    string softwareTitle;
    string invoiceNumber;

    public SoftwareTitles(string softwareTitle, string invoiceNumber)
    {
        this.softwareTitle = softwareTitle;
        this.invoiceNumber = invoiceNumber;
    }

    string InvoiceNumber
    {           
        get
        {
            return this.invoiceNumber;
        }
    }

    string SoftwareTitle
    {
        get
        {
            return this.softwareTitle;
        }
    }
}

And now I'm adding the values from the sql server database to the list defines as follows:

 public List<SoftwareTitles> SoftwareListRetrieve()
    {
        ConnectionToSql con1 = new ConnectionToSql();
        string connectionString = con1.ConnectionStringMethod();
        SqlConnection sqlConnection = new SqlConnection(connectionString);
        SqlCommand cmd2 = new SqlCommand("SelectionOfSoftwareTitles", sqlConnection);
        cmd2.CommandType = CommandType.StoredProcedure;
        sqlConnection.Open();
        SqlDataReader dr2 = cmd2.ExecuteReader();

        if (dr2.HasRows)
        {
            while (dr2.Read())
            {
                String softwareTitle = (String)dr2[0];
                String invoiceNumber = (String)dr2[1];
                SoftwareTitles s1 = new SoftwareTitles(softwareTitle, invoiceNumber);
                softwareTitlesList.Add(s1);
            }
        }

        sqlConnection.Close();
        dr2.Close();

        return softwareTitlesList;
    }

I want to find out the software title for every occurence of invoice number by looping through List<>. And I don't kno开发者_运维技巧w how ? I have tried to loop through the List<> by the following code. I wanted to use something like contains i.e., softwareTitlesList[i].contains but seems like there is no such property or method

 for(int i=0; i<softwareTitlesList.Count;i++)
        {
            softwareTitlesList[i]. [BUT IT IS NOT SUGGESTING ME ANYTHING]
        }

I'm stuck with this from morning. I don't how to solve this dilemma.

Please help me

Thanks in anticipation

search for an invoice number

string invoiceNumber = "111111111";

using linq

IList<string> titles = softwareTitlesList
    .Where(st => st.InvoiceNumber == invoiceNumber)
    .Select(st => st.SoftwareTitle);

or

IList<string> titles = softwareTitlesList
    .Where(st => st.InvoiceNumber.Contains(invoiceNumber))
    .Select(st => st.SoftwareTitle);

w/o using linq, it's still pretty basic

IList<string> titles = new List<string>();
foreach(var softwareTitle in softwareTitlesList)
{
    if (softwareTitle.InvoiceNumber.Contains(invoiceNumber))
        titles.Add(softwareTitle.SoftwareTitle);
}

you could also rewrite your class like this:

public class SoftwareTitles
{
    public SoftwareTitles(string softwareTitle, string invoiceNumber)
    {
        SoftwareTitle = softwareTitle;
        InvoiceNumber = invoiceNumber;
    }

    public string InvoiceNumber { get; private set; }

    public string SoftwareTitle { get; private set; }
}