由于此错误，我的代码行无法工作？

Question

So basically here is the problem, I have tried many ways to fix it but none of them worked ! Error is getting at this line : Templist.Add((string)result["titre"]; . Templist is the error !

private List<string> ReadNews()
{
    string SqlText = "SELECT * FROM nom_table"; 
    List<string> Templist; 
    MySqlConnection SqlConnection = new 
    MySqlConnection(TheConnectionString);
    MySqlCommand SqlCommand = new 
    MySqlCommand(SqlText,SqlConnection);


    MySqlDataReader result = SqlCommand.ExecuteReader();

    while (result.Read())
    {
        Templist.Add((string)result["titre"]);
    }

    return Templist;
}

Answer 1

Because you haven't initialized the Templist , until you initialize/assign an instance the declared variable( Templist ) will be null, and you are not able to add something to null that is what the error message says. The code should be :

List<string> Templist =  new List<string>();

One more thing I would like to add here is the usage of using for proper disposal of the objects, and also specified column names instead for * . Consider the modified snippets below:

private List<string> ReadNews()
{
    string SqlText = "SELECT titre FROM nom_table";
    List<string> Templist = new List<string>();
    using (SqlConnection SqlConnection = new MySqlConnection(TheConnectionString))
    {
        using (MySqlCommand SqlCommand = new MySqlCommand(SqlText, SqlConnection))
        {
            using (MySqlDataReader result = SqlCommand.ExecuteReader())
            {
                while (result.Read())
                {
                    Templist.Add((string)result["titre"]);
                }
            }

        }
    }
    return Templist;
}

Answer 2

Your Templist should be initialized before use. Change your declaration line to this:

List<string> Templist = new List<string>();

Answer 3

Templist is null, you haven't created an instance yet. Initialize:

List<string> Templist = new List<string>();