How Span<T> provides contiguous memory slicing without allocating sub-arrays or substrings:

// Parsing date string '2026-08-22' without allocating strings for Year, Month, Day
string dateStr = "2026-08-22";
ReadOnlySpan<char> span = dateStr.AsSpan();

int year = int.Parse(span.Slice(0, 4));
int month = int.Parse(span.Slice(5, 2));
int day = int.Parse(span.Slice(8, 2));

span.Slice() is a pointer arithmetic operation on the stack ($O(1)$ time, 0 heap allocations). Unlike string.Substring() which allocates a new string on the managed heap for each segment!

Span<T> is defined as a ref struct, meaning it can only live on the execution stack and cannot be boxed or escape to the heap. This enables extreme memory safety.

All standard .NET BCL methods (int.Parse, Guid.Parse, Utf8Parser) now accept ReadOnlySpan<char> and ReadOnlySpan<byte> for maximum throughput.