Awesome string formatting

The next release of C# 6 has some amazing new features. In a series of blog posts I will cover some of them.

• Chained null checks
• The nameof operator
• Awesome string formatting (this one)
• Expression-bodied methods
• Auto-property initializers
• Initialize a Dictionary with index initializers

Using the versatile string.Format required a lot of typing and keeping the numbed placeholders in sync with the method parameters.

var numerator = 1;
var denominator = 2;

Console.WriteLine("Fraction {0}/{1}", numerator, denominator);

// Output:
//   Fraction 1/2

In C# 6 is it a lot easier with String interpolation:

var numerator = 1;
var denominator = 2;

Console.WriteLine("Fraction {numerator}/{denominator}");

// Output:
//   Fraction 1/2

Referencing the variable, property or field directly within the string. It is even possible to access properties or use expressions.

public class Person
{
  public string Name { get; set; }
  public Address HomeAddress { get; set; }

  public override string ToString()
  {
    return string.Format("{Name} lives in {HomeAddress.City}.");
  }
}

The string.Format is not event needed, but use the shorthand notation $.

return $("{Name} lives in {HomeAddress.City}.";

This is easily combinable with an expression and the null-conditional operator (?.) operator.

return $"{Name} lives in {HomeAddress?.City ?? "City unknown"}.";