If the most‐significant bit of the one byte of this stream at the current cursor location is set, assign to the specified length the four‐byte, two's complement integer (in host byte order) comprised of the four bytes of this stream at the current cursor location (in network byte order) with the most‐significant bit unset; otherwise, assign to length the one‐byte, two's complement integer comprised of the one byte of this stream at the current cursor location. Update the cursor location and return a reference to this stream. If this stream is initially invalid, this operation has no effect. If this function otherwise fails to extract a valid value, this stream is marked invalid and the value of length is undefined. Note that the value will be zero‐extended.