read-byte

read-byte Function

Syntax:

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

Arguments and Values:

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.

Description:

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.

Examples:

(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 

Side Effects:

Modifies stream.

Exceptional Situations:

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.

See Also:

read-char, read-sequence, write-byte

Expanded Reference: read-byte

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