CSHARP

c# 10 null checl

// As of C# 10 (.NET 6)
ArgumentNullException.ThrowIfNull(name);

c# null check

public static int CountNumberOfSInName(string name)
{
  if (name == null)
  {
    throw new ArgumentNullException(nameof(name));
  }

  return name.Count(c => char.ToLower(c).Equals('s'));
}

c# null check

if (name is null)
  {
    throw new ArgumentNullException(nameof(name));
  }