C# defines a number of aliases for CLR types. They may be used interchangably, and even mixed together, e.g:
string x = new System.String(' ', 5);.
What is the difference between using “String” and “string” (“Object” vs “object” etc.)? both are exactly equivalent, so pick the one you like best and stick with it.
System.Text.StringBuilder sb = new System.Text.StringBuilder(); sb.Append(" "); sb.Append(s); writer.WriteLine(sb.ToString());