A new way to format strings in C# 6

In C# 5 we often format strings with the string.Format function. It requires a format string and then a number of parameters that are passed into the format string. C# 6 has a nice addition which simplifies that syntax.

Let’s start with the following Rockband object:

public class Rockband
{
	public string Name { get; }
	public int NumberOfMembers { get; }
	public decimal ConcertFee { get; }

	public Rockband(string name, int numberOfMembers, decimal concertFee)
	{
		Name = name;
		NumberOfMembers = numberOfMembers;
		ConcertFee = concertFee;
	}

	public string GetFancyName()
	{
		return Name.ToUpper();
	}
}

The fancy name is not too fancy but that’s not important now.

In C# 5 we could use string.Format as follows:

Rockband metallica = new Rockband("Metallica", 4, 50);
string formatExampleOne = string.Format("The band is called {0}, they have the fancy name of {1}, they have {2} members and require {3:c} for a concert."
	, metallica.Name, metallica.GetFancyName(), metallica.NumberOfMembers, metallica.ConcertFee);
Debug.WriteLine(formatExampleOne);

formatExampleOne will be…

The band is called Metallica, they have the fancy name of METALLICA, they have 4 members and require £50.00 for a concert.

The currency will differ depending on the culture settings of the thread the code is running under. The point is that you can add a number of format modifiers such as “:c” for currency. You’ll find a long list of examples here on MSDN.

In C# 6 we can rewrite the above with the ‘$’ operator in front of the string literal and actual C# code within the brackets as follows:

string formatExampleTwo = $"The band is called {metallica.Name}, they have the fancy name of {metallica.GetFancyName()}, they have {metallica.NumberOfMembers} members and require {metallica.ConcertFee:c} for a concert.";

You’ll also get IntelliSense when you type “{metallica. “. You’ll also see that additional modifiers such as the currency modifier are also supported.

View all various C# language feature related posts here.