Cheh: Data Binding in C#

• In expressions with the null-conditional operators ?. and ?[], you can use the null-coalescing operator to provide an alternative expression to evaluate in case the result of the expression with null-conditional operations is null:
  C#

  double SumNumbers(List<double[]> setsOfNumbers, int indexOfSetToSum)
  {
      return setsOfNumbers?[indexOfSetToSum]?.Sum() ?? double.NaN;
  }
  
  var sum = SumNumbers(null, 0);
  Console.WriteLine(sum);  // output: NaN

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