Question

What’s the most efficient way to concatenate strings?

Answer 1

The StringBuilder.Append() method is much better than using the + operator. But I’ve found that, when executing 1000 concatenations or less, String.Join() is even more efficient than StringBuilder.

StringBuilder sb = new StringBuilder(); sb.Append(someString); 

The only problem with String.Join is that you have to concatenate the strings with a common delimiter.

Edit: as @ryanversaw pointed out, you can make the delimiter string.Empty.

string key = String.Join('_', new String[]  { 'Customers_Contacts', customerID, database, SessionID });