string name = "Samantha Jones";

// getting the lengths of the first and last names

int lengthOfFirst = name.IndexOf(' ');
int lengthOfLast = name.Length - lengthOfFirst - 1;

// Using Substring

string firstName = name.Substring(
  startIndex: 0,
  length: lengthOfFirst);

string lastName = name.Substring(
  startIndex: name.Length - lengthOfLast,
  length: lengthOfLast);

WriteLine($"First name: {firstName}, Last name: {lastName}");

// Using spans

ReadOnlySpan<char> nameAsSpan = name.AsSpan();
ReadOnlySpan<char> firstNameSpan = nameAsSpan[0..lengthOfFirst];
ReadOnlySpan<char> lastNameSpan = nameAsSpan[^lengthOfLast..^0];

WriteLine("First name: {0}, Last name: {1}",
  arg0: firstNameSpan.ToString(),
  arg1: lastNameSpan.ToString());