System.ReadOnlySpanExtensions.Slice C# (CSharp) Method

        public static ReadOnlySpan<char> Slice(this string text, int start, int length)
        {
            if (text == null)
                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.text);
            int textLength = text.Length;
            if ((uint)start > (uint)textLength || (uint)length > (uint)(textLength - start))
                ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.start);

            unsafe
            {
                byte* byteOffset = ((byte*)StringAdjustment) + (uint)(start * sizeof(char));
                return new ReadOnlySpan<char>(Unsafe.As<Pinnable<char>>(text), (IntPtr)byteOffset, length);
            }
        }