Question

Last time I had a similar question, but we figured out if initialize and set a value for the variable before the logic statement then I can use the value that was generated within the logic statement.

This time, I want to call one of two method overloads depending on if the connection string is empty or not. Like so.

if (ConnectionString != "") // if there is something in the config file work with it
{
  SqlConnection dataConnection = new SqlConnection(ConnectionString);
}
else
{
  SqlConnection dataConnection = new SqlConnection();
}

try {
  // ...

The problem is that anything in the try block fails because it does not know about the dataConnection.

How can do I do this in a way to make it work?

Answer 1

Declare it (uninitialized) outside:

SqlConnection conn;
if(string.IsNullOrEmpty(connectionString)) {
    conn = new SqlConnection();
} else {
    conn = new SqlConnection(connectionString);
}

If the logic is simple, a conditional is possible too:

SqlConnection conn = string.IsNullOrEmpty(connectionString)
     ? new SqlConnection() : new SqlConnection(connectionString);

The latter is much easier to use with a using block, as it can be done inline.