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

You are using a trivial example where there is not much of a difference. However, if you have a long string with many parameters it is much nicer to be able to use a format string instead of many, many + signs and line breaks.

It also allows you to format numerical data as you wish, i.e., currency, dates, etc.

Answer 2

You picked too simple of an example.

String formatting:

• allows you to use the same variable multiple times: ("{0} + {0} = {1}", x, 2*x)
• automatically calls ToString on its arguments: ("{0}: {1}", someKeyObj, someValueObj)
• allows you to specify formatting: ("The value will be {0:3N} (or {1:P}) on {2:MMMM yyyy gg}", x, y, theDate)
• allows you to set padding easily: (">{0,3}<", "hi"); // ">hi <"

Answer 3

String formatting allows you to keep the format string separate, and use it where it's needed properly without having to worry about concatenation.

string greeting = "Hello {0}!";
Console.WriteLine(greeting, name);

As for why you would use it in the exact example you gave... force of habit, really.

Answer 4

I think a good example is about i18n and l10n

If you have to change a string between different languages, this: "bla "+variable+"bla bla.." Will give problems to a program used to create sobstitution for your strings if you use a different language

while in this way: "bla {0} blabla" is easily convertible (you will get {0} as part of the string)

Answer 5

Formatting is usually preferred for most of the reasons explained by other members here. There are couple more reasons I want to throw in from my short programming experience:

• Formatting will help in generating Culture aware strings.
• Formatting is more performant than concatenation. Remember, every concatenation operation will involve creation of temporary intermediate strings. If you have a bunch of strings you need to concatenate, you are better off using String.Join or StringBuilder.

Answer 6

In addition to reasons like Ignacio's, many (including me) find String.Format-based code much easier to read and alter.

string x = String.Format(
  "This file was last modified on {0} at {1} by {2}, and was last backed up {3}."
  date, time, user, backupDate);

vs.

string x = "This file was last modified on " + date + " at "
+ time + " by " + user + " and was last backed up " + backupDate + ".";