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#Welcome to the CSharp7Features wiki!

Binary Literals & Digits Separators

New langauge Syntax to improve readability for numeric constants.

int binary = 0b1001_1010_1001_0100;
int hex = 0x1c_a0_41_fe;
double real = 1_00.99_9e-1_000;

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Out variables

Declare out variablie inline.

public static void OutVarTest(string @int)
{
  int.TryParse(@int, out int t);
  Console.WriteLine(t);
}

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Local Functions

Nesting functions inside other functions to limit their scope and visibility.

• Better performance

• Reduced memory pressure

  public static void BasicExample() { // Lambda Function Action lambdaFun = () => Console.WriteLine("I'm Lambda"); lambdaFun.Invoke(); // Local Functions Basic void EmptyLocalFunction() { Console.WriteLine("I'm Local"); }; EmptyLocalFunction(); }

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Ref Returns

var array = new[] { 1, 2, 3, 4, 5};
ref int GetItem(int[] arrayParam, int index) => ref arrayParam[index];
ref int item = ref GetItem(array, 1);

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Throw expressions

You can throw exceptions in code constructs that previously were not allowed because throw was a statement.

• Null coalescing expressions

• Some lambda expressions

• Expression-bodied

  public static double Divide(int x, int y) { return y != 0 ? x % y : throw new DivideByZeroException(); } var a = Divide(10, 0);

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Expression-bodied

C # 6 expression-bodied members expanded

• Constructors
• Finalizers
• Indexers See the code example!

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Generalized async return

Define custom return types on async methods

• ValueTask
• Designed for the very scenario

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Tuples

A tuple is a data structure that has a specific number and sequence of Elements.

• ValueTuple
• Immutable

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Destruction

Destruct an object to a tuple

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Pattern Matching

Pattern matching (similar to a switch statement that works on the “shape” of the data, for example its type, rather than just the value)

• Constant patterns
• Type patterns
• Var patterns