read-byte (Function)

Syntax:

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