String output: format or concat in C#?

Question

Let\'s say that you want to output or concat strings. Which of the following styles do you prefer?

• var p = new { FirstName = \"Bill\", LastName = \"Ga

Answer 1

I choose based on readability. I prefer the format option when there's some text around the variables. In this example:

Console.WriteLine("User {0} accessed {1} on {2}.", 
                   user.Name, fileName, timestamp);

you understand the meaning even without variable names, whereas the concat is cluttered with quotes and + signs and confuses my eyes:

Console.WriteLine("User " + user.Name + " accessed " + fileName + 
                  " on " + timestamp + ".");

(I borrowed Mike's example because I like it)

If the format string doesn't mean much without variable names, I have to use concat:

   Console.WriteLine("{0} {1}", p.FirstName, p.LastName);

The format option makes me read the variable names and map them to the corresponding numbers. The concat option doesn't require that. I'm still confused by the quotes and + signs, but the alternative is worse. Ruby?

   Console.WriteLine(p.FirstName + " " + p.LastName);

Performance wise, I expect the format option to be slower then the concat, since format requires the string to be parsed. I don't remember having to optimize this kind of instruction, but if I did, I'd look at string methods like Concat() and Join().

The other advantage with format is that the format string can be put in a configuration file. Very handy with error messages and UI text.