70 lines
5.4 KiB
HTML
70 lines
5.4 KiB
HTML
<!-- Common Lisp HyperSpec (TM), version 7.0 generated by Kent M. Pitman on Mon, 11-Apr-2005 2:31am EDT -->
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<TITLE>CLHS: Function READ-BYTE</TITLE>
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<A NAME="read-byte"><I>Function</I> <B>READ-BYTE</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>read-byte</B> <I>stream <TT>&optional</TT> eof-error-p eof-value</I> => <I>byte</I><P>
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<P>
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<P><B>Arguments and Values:</B><P>
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<P>
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<I>stream</I>---a <A REL=DEFINITION HREF="26_glo_b.htm#binary"><I>binary</I></A> <A REL=DEFINITION HREF="26_glo_i.htm#input"><I>input</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>stream</I></A>. <P>
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<I>eof-error-p</I>---a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. The default is <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A>. <P>
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<I>eof-value</I>---an <A REL=DEFINITION HREF="26_glo_o.htm#object"><I>object</I></A>. The default is <A REL=DEFINITION HREF="a_nil.htm#nil"><B>nil</B></A>. <P>
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<I>byte</I>---an <A REL=DEFINITION HREF="26_glo_i.htm#integer"><I>integer</I></A>, or the <I>eof-value</I>. <P>
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<P><B>Description:</B><P>
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<P>
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<A REL=DEFINITION HREF="#read-byte"><B>read-byte</B></A> reads and returns one byte from <I>stream</I>. <P>
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If an <A REL=DEFINITION HREF="26_glo_e.htm#end_of_file"><I>end of file</I></A>[2] occurs and <I>eof-error-p</I> is <A REL=DEFINITION HREF="26_glo_f.htm#false"><I>false</I></A>, the <I>eof-value</I> is returned. <P>
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<P><B>Examples:</B><P>
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<PRE>
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(with-open-file (s "temp-bytes"
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:direction :output
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:element-type 'unsigned-byte)
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(write-byte 101 s)) => 101
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(with-open-file (s "temp-bytes" :element-type 'unsigned-byte)
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(format t "~S ~S" (read-byte s) (read-byte s nil 'eof)))
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>> 101 EOF
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=> NIL
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</PRE>
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</TT> <P>
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<P><B>Side Effects:</B><P>
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<P>
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Modifies <I>stream</I>. <P>
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<P><B>Affected By:</B> None.
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<P>
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<P><B>Exceptional Situations:</B><P>
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<P>
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Should signal an error of <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> <A REL=DEFINITION HREF="e_tp_err.htm#type-error"><B>type-error</B></A> if <I>stream</I> is not a <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>stream</I></A>. <P>
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Should signal an error of <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> <A REL=DEFINITION HREF="e_error.htm#error"><B>error</B></A> if <I>stream</I> is not a <A REL=DEFINITION HREF="26_glo_b.htm#binary"><I>binary</I></A> <A REL=DEFINITION HREF="26_glo_i.htm#input"><I>input</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#stream"><I>stream</I></A>. <P>
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If there are no <A REL=DEFINITION HREF="26_glo_b.htm#byte"><I>bytes</I></A> remaining in the <I>stream</I> and <I>eof-error-p</I> is <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A>, an error of <A REL=DEFINITION HREF="26_glo_t.htm#type"><I>type</I></A> <A REL=DEFINITION HREF="e_end_of.htm#end-of-file"><B>end-of-file</B></A> is signaled. <P>
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<P><B>See Also:</B><P>
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<P>
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<A REL=DEFINITION HREF="f_rd_cha.htm#read-char"><B>read-char</B></A>, <A REL=DEFINITION HREF="f_rd_seq.htm#read-sequence"><B>read-sequence</B></A>, <A REL=DEFINITION HREF="f_wr_by.htm#write-byte"><B>write-byte</B></A> <P>
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<P><B>Notes:</B> None.
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<P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issues</A>, <I>not part of the specification</I>, apply to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss285.htm">READ-AND-WRITE-BYTES:NEW-FUNCTIONS</A><LI> <A REL=CHILD HREF="../Issues/iss013.htm">ARGUMENTS-UNDERSPECIFIED:SPECIFY</A><P></UL><HR>
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