75 lines
6.7 KiB
HTML
75 lines
6.7 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-LINE</TITLE>
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<H1><A REV=MADE HREF="http://www.lispworks.com/"><IMG WIDTH=80 HEIGHT=65 ALT="[LISPWORKS]" SRC="../Graphics/LWSmall.gif" ALIGN=Bottom></A><A REL=TOP HREF="../Front/index.htm"><IMG WIDTH=237 HEIGHT=65 ALT="[Common Lisp HyperSpec (TM)]" SRC="../Graphics/CLHS_Sm.gif" ALIGN=Bottom></A> <A REL=PREV HREF="f_wr_cha.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Previous]" SRC="../Graphics/Prev.gif" ALIGN=Bottom></A><A REL=UP HREF="c_stream.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Up]" SRC="../Graphics/Up.gif" ALIGN=Bottom></A><A REL=NEXT HREF="f_wr_stg.htm"><IMG WIDTH=40 HEIGHT=40 ALT="[Next]" SRC="../Graphics/Next.gif" ALIGN=Bottom></A></H1>
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<A NAME="read-line"><I>Function</I> <B>READ-LINE</B></A> <P>
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<P><B>Syntax:</B><P>
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<P>
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<B>read-line</B> <I><TT>&optional</TT> input-stream eof-error-p eof-value recursive-p</I><P> => <I>line, missing-newline-p</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>input-stream</I>---an <A REL=DEFINITION HREF="26_glo_i.htm#input"><I>input</I></A> <A REL=DEFINITION HREF="26_glo_s.htm#stream_designator"><I>stream designator</I></A>. The default is <A REL=DEFINITION HREF="26_glo_s.htm#standard_input"><I>standard input</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>recursive-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_f.htm#false"><I>false</I></A>. <P>
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<I>line</I>---a <A REL=DEFINITION HREF="26_glo_s.htm#string"><I>string</I></A> or the <I>eof-value</I>. <P>
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<I>missing-newline-p</I>---a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A>. <P>
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<P><B>Description:</B><P>
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<P>
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Reads from <I>input-stream</I> a line of text that is terminated by a <A REL=DEFINITION HREF="26_glo_n.htm#newline"><I>newline</I></A> or <A REL=DEFINITION HREF="26_glo_e.htm#end_of_file"><I>end of file</I></A>. <P>
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If <I>recursive-p</I> is <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A>, this call is expected to be embedded in a higher-level call to <A REL=DEFINITION HREF="f_rd_rd.htm#read"><B>read</B></A> or a similar <A REL=DEFINITION HREF="26_glo_f.htm#function"><I>function</I></A> used by the <A REL=DEFINITION HREF="26_glo_l.htm#lisp_reader"><I>Lisp reader</I></A>. <P>
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The <A REL=DEFINITION HREF="26_glo_p.htm#primary_value"><I>primary value</I></A>, <I>line</I>, is the line that is read, represented as a <A REL=DEFINITION HREF="26_glo_s.htm#string"><I>string</I></A> (without the trailing <A REL=DEFINITION HREF="26_glo_n.htm#newline"><I>newline</I></A>, if any). If <I>eof-error-p</I> is <A REL=DEFINITION HREF="26_glo_f.htm#false"><I>false</I></A> and the <A REL=DEFINITION HREF="26_glo_e.htm#end_of_file"><I>end of file</I></A> for <I>input-stream</I> is reached before any <A REL=DEFINITION HREF="26_glo_c.htm#character"><I>characters</I></A> are read, <I>eof-value</I> is returned as the <I>line</I>. <P>
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The <A REL=DEFINITION HREF="26_glo_s.htm#secondary_value"><I>secondary value</I></A>, <I>missing-newline-p</I>, is a <A REL=DEFINITION HREF="26_glo_g.htm#generalized_boolean"><I>generalized boolean</I></A> that is <A REL=DEFINITION HREF="26_glo_f.htm#false"><I>false</I></A> if the <I>line</I> was terminated by a <A REL=DEFINITION HREF="26_glo_n.htm#newline"><I>newline</I></A>, or <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A> if the <I>line</I> was terminated by the <A REL=DEFINITION HREF="26_glo_e.htm#end_of_file"><I>end of file</I></A> for <I>input-stream</I> (or if the <I>line</I> is the <I>eof-value</I>). <P>
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<P><B>Examples:</B><P>
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<P>
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<PRE>
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(setq a "line 1
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line2")
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=> "line 1
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line2"
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(read-line (setq input-stream (make-string-input-stream a)))
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=> "line 1", <A REL=DEFINITION HREF="26_glo_f.htm#false">false</A>
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(read-line input-stream)
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=> "line2", <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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(read-line input-stream nil nil)
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=> NIL, <A REL=DEFINITION HREF="26_glo_t.htm#true">true</A>
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</PRE>
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</TT> <P>
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<P><B>Side Effects:</B> None.
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<P>
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<P><B>Affected By:</B><P>
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<P>
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<A REL=DEFINITION HREF="v_debug_.htm#STstandard-inputST"><B>*standard-input*</B></A>, <A REL=DEFINITION HREF="v_termin.htm#STterminal-ioST"><B>*terminal-io*</B></A>. <P>
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<P><B>Exceptional Situations:</B><P>
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<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 before any characters are read in the line, an error is signaled if <I>eof-error-p</I> is <A REL=DEFINITION HREF="26_glo_t.htm#true"><I>true</I></A>. <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_rd.htm#read"><B>read</B></A> <P>
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<P><B>Notes:</B><P>
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<P>
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The corresponding output function is <A REL=DEFINITION HREF="f_wr_stg.htm#write-line"><B>write-line</B></A>. <P>
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<P><HR>The following <A REL=META HREF="../Front/X3J13Iss.htm">X3J13 cleanup issue</A>, <I>not part of the specification</I>, applies to this section:<P><UL><LI> <A REL=CHILD HREF="../Issues/iss013.htm">ARGUMENTS-UNDERSPECIFIED:SPECIFY</A><P></UL><HR>
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