SqlDataReader to string[]

Question

why the following code doesn't work?

internal static string[] GetToolsForRole(string selectedRole) {
  string[] tempStr;
  ArrayList myAL = new ArrayList();
  SqlCommand cmd = new SqlCommand("usp_TD_SelectByRoleName");
  cmd.CommandType = CommandType.StoredProcedure;

  cmd.Parameters.Add("@role", SqlDbType.NVarChar, 50).Value = selectedRole;

  SqlConnection myConnection = Util.GetConnection();
  cmd.Connection = myConnection;
  SqlDataReader reader = cmd.ExecuteReader();

  int i = 0;
  while (reader.Read()) {
    tempStr[i] = reader["TD_Name"].ToString();
    i++;
  }

  return tempStr;
}

Just wondering, why not ArrayList? Sure List<T> is strongly typed, but with just strings isn't ArrayList just fine? — Hogan
– Hogan, Commented Mar 20, 2011 at 16:33
@Hogan: Huh? How is ArrayList any better with strings? You should always use List<T>. — SLaks
– SLaks, Commented Mar 20, 2011 at 17:25
@SLaks : I would guess it was marginally faster unless it is implemented strangely. — Hogan
– Hogan, Commented Mar 20, 2011 at 17:31
@Hogan: An ArrayList will never be faster than a List<T>. (I have no sources for that statement) — SLaks
– SLaks, Commented Mar 20, 2011 at 17:33
@Slaks : My understanding is parameterized types are instantiated at runtime -- this would have to require more overhead in time and memory than pre-compiled code which just manages pointers. Am I missing something? (I will admit we are talking about relatively small differences). — Hogan
– Hogan, Commented Mar 20, 2011 at 17:57

SLaks · Accepted Answer · 2011-03-20 14:08:29Z

2

Arrays don't work like that.

You should use a List<string>, and call the Add method.

To use an array,you need to create a new array by writing tempStr = new string[size]. Arrays cannot be resized in-place.

answered Mar 20, 2011 at 14:08

SLaks

891k182 gold badges1.9k silver badges2k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

eyalb Over a year ago

i changed to List<string>, but still get "Use of unassigned local variable 'tempStr'"

SLaks Over a year ago

@eyalb: You need to put a new List<string> into your variable.

Hogan · Accepted Answer · 2011-03-20 14:09:28Z

0

You never allocate tempStr.

Try this in loop:

myAL.Add(reader["TD_Name"].ToString());

Then this at return

return (String[]) myAL.ToArray( typeof( string ) );

You won't need (remove) the i and tempStr variables.

answered Mar 20, 2011 at 14:09

Hogan

70.7k10 gold badges83 silver badges119 bronze badges

Collectives™ on Stack Overflow

SqlDataReader to string[]

2 Answers 2

2 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related