read-byte stream &optional eof-error-p eof-value → byte

stream — a binary input stream.

eof-error-p — a generalized boolean. The default is true.

eof-value — an object. The default is nil.

byte — an integer, or the eof-value.

read-byte reads and returns one byte from stream.

If an end of file₂ occurs and eof-error-p is false, the eof-value is returned.

 (with-open-file (s "temp-bytes" 
                     :direction :output 
                     :element-type 'unsigned-byte) 
    (write-byte 101 s)) → 101 
 (with-open-file (s "temp-bytes" :element-type 'unsigned-byte) 
    (format t "~S ~S" (read-byte s) (read-byte s nil 'eof))) 
⊳ 101 EOF 
→ NIL

Modifies stream.

Should signal an error of type type-error if stream is not a stream.

Should signal an error of type error if stream is not a binary input stream.

If there are no bytes remaining in the stream and eof-error-p is true, an error of type end-of-file is signaled.

read-char, read-sequence, write-byte