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c#listvariablesmethods
Kestami
Kestami

Reputation: 2073

Using a variable from a returned list<> method

hopefully a pretty simple question this time. I have a Select method in a database connector class, which is as follows;

  public List <string> [] Select(string mQuery)
{

    //Create a list to store the result
    List<string>[] datalist = new List<string>[1];
    datalist[0] = new List<string>();


    //Open connection
    if (this.OpenConnection() == true)
    {
        //Create Command
        MySqlCommand cmd = new MySqlCommand(mQuery, mConnection);
        //Create a data reader and Execute the command
        MySqlDataReader dataReader = cmd.ExecuteReader();

        //Read the data and store them in the list
        while (dataReader.Read())
        {
            datalist[0].Add(dataReader["id"] + "");

        }

        //close Data Reader
        dataReader.Close();

        //close Connection
        this.CloseConnection();

        //return list to be displayed
        return datalist;
    }
    else
    {
        return datalist;
    }
}

When i want to access "datalist" i'm assuming i call it like so;

      results = mDB.Select(mQuery);

But because the returned value is a list, do i need to assign this variable to a new list, like so;?

 List<string>[] results = new List<string>[1];
                       results[0] = new List<string>();
                       results = mDB.Select(mQuery);
                       string result = results[0].ToString();

                       MessageBox.Show(result);

This message box simply produces "System.Collections.Generic.List1(System.String)"

Any ideas about the logic of what i'm doing wrong?

Upvotes: 0

Views: 1894

Answers (2)

Stuart Golodetz
Stuart Golodetz

Reputation: 20616

If what you're trying to do is display the contents of a list in e.g. a comma-separated way, you can do something like this:

MessageBox.Show(string.Join(",", list));

The reason you're getting "System.Collections.Generic.List1(System.String)" is that ToString for a List just returns a string representation of its type.

Also, as others have pointed out, you should lose the array. What you're after is something like:

public List<string> Select(string mQuery)
{
    //...
}

List<string> list = mDB.Select(mQuery);
MessageBox.Show(string.Join(",", list));

Upvotes: 0

Alexander R
Alexander R

Reputation: 2476

Try not wrapping your list in an array?

 List<string> results = new List<string>();
 results = mDB.Select(mQuery);
 string result = results[0].ToString();

 MessageBox.Show(result);

Either way, the issue is that you were trying to display a list, which by default just returns it's type. You should display the members of the list, not the list itself.

Upvotes: 2

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