c# string formatting

Question

I m curious why would i use string formatting while i can use concatenation such as

Console.WriteLine(\"Hello {0} !\", name);

Console.WriteLine(\"Hello \"+          


        

Answer 1

There isn't a singular correct answer to this question. There are a few issues you want to address:

Performance

The performance differences in your examples (and in real apps) are minimal. If you start writing MANY concatenations, you will gradually see better memory performance with the formatted string. Refer to Ben's answer

Readability

You will be better off with a formatted string when you have formatting, or have many different variables to stringify:

string formatString = "Hello {0}, today is {1:yyyy-MM-dd}";
Console.WriteLine(formatString, userName, Date.Today);

Extensibility

Your situation will determine what's best. You tell me which is better when you need to add an item between Username and Time in the log:

Console.WriteLine(
   @"Error! 
    Username: " + userName + "
    Time: " + time.ToString("HH:mm:ss") + "
    Function: " + functionName + "
    Action: " + actionName + "
    status: " + status + "
   ---");

or

Console.WriteLine(@"Error! 
    Username: {0}
    Time: {1}
    Function: {2}
    Action: {3}
    status: {4}
   ---",
    username, time.ToString("HH:mm:ss"), functionName, actionName, status);

Conclusion

I would choose the formatted string most of the time... But I wouldn't hesitate at all to use concatenation when it was easier.