Favorites C# 6 and 7 features

C# Version Reference 

•   What's new in C#? 

Function returning multiple values via tuple

        
static (string Alpha, string Beta) GetLetters () {
    return ("A", "B");
}
static void Main(string[] args) {
    Console.WriteLine(GetLetters());         
}

Result

(A, B)

Tracing function and parameter names

        
static void MyFunction(string myVariable) {
    Console.WriteLine($"  function: {nameof(MyFunction)}, variable: {nameof(myVariable)} = {myVariable} ");
}
static void Main(string[] args) {
    MyFunction("Fred");
}

Result

 function: MyFunction, variable: myVariable = Fred

Null-conditional operators

        
class Person {
    public string FirstName { get; set;}
}
static void HandleNull(Person p)
{
    var firstName = p?.FirstName; // return null if p or p.FirstName is null
    Console.WriteLine(firstName);
}
static void Main(string[] args) {
    HandleNull(new Person { FirstName = "Fred" });
    HandleNull(null);
}

Result

Fred

Property Initializer

        
   public static int BirthYear { get; set; } = 1974;
   public static int BirthYear2 { get; } = 1974;

Out Variables

        
if (int.TryParse(input, out int result))
    WriteLine(result);
else
    WriteLine("Could not parse input");

Local Functions

        
public static int Add(string op, int i1, int i2)
{
    switch(op)
    {
        case "add": return add(i1, i2);
        case "sub": return sub(i1, i2);
        default: throw new InvalidOperationException();
    }
            
    int add(int a, int b)
    {
        return a + b;
    }
    int sub(int a, int b)
    {
        return a - b;
    }
}

Numeric literal syntax improvements

        
static void Main(string[] args) {
    const int four = 0b0100; // Binary notation support
    const long hundredThousand = 100_000; // The digit separator can appear anywhere in the constant.
    Console.WriteLine($"four:{four}");
    Console.WriteLine($"hundredThousand:{hundredThousand}");
}

Result

4
100000