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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><!-- General IFxx Construction --><HTML><HEAD><TITLE>General IFxx Construction</TITLE></HEAD><BODY BACKGROUND="spiral.gif" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#990099" ALINK="#FF0000"><TABLE WIDTH="98%"><TR><TD WIDTH=60 VALIGN=BOTTOM NOWRAP><IMG SRC="transp.gif" ALT="" WIDTH=60 HEIGHT=20></TD><TD><!-- Ab hier Seitentext: --><BIG><BR><P><STRONG><U>III.10.1 General IFxx Construction</U></STRONG></P><P>Simple IFxx ... ENDIF constructions can be used to assemble a number ofenclosed statements only, if a particluar condition is met:</P><P><BLOCKQUOTE><STRONG><PRE>IFxx <condition> <statement 1> <statement 2> . ;assembled if <condition> is TRUE . <statement n>ENDIF</PRE></STRONG></BLOCKQUOTE></P><P>The statements 1 through n are assembled if <condition> is TRUE, otherwisethey are ignored.</P><P>If it should be possible to select two variants of code depending on aparticular condition, this can be done with an IFxx .. ELSE .. ENDIFconstruction. If the <condition> in the IFxx statement is TRUE, thenstatements 1 to n are assembled and the statements n+1 to n+m are ignored.</P><P><BLOCKQUOTE><STRONG><PRE>IFxx <condition> <statement 1> . ;assembled if <condition> is TRUE <statement n>ELSE <statement n+1> . ;assembled if <condition> is FALSE <statement n+m>ENDIF</PRE></STRONG></BLOCKQUOTE></P><P>Should <condition> be FALSE, it is exactly vice versa! That means thestatements 1 to n are ignored and the statements n+1 to n+m are assembled.This works also, if the IFxx or ELSE branches contain no statements at all.</P><P>Whenever more than two cases have to be distinguished, a corresponding numberof ELSEIFxx branches can be inserted between the IFxx and the ELSE branch.In such an IFxx .. ELSEIFxx .. ELSE .. ENDIF construction, only the statementsin the branch with the first TRUE condition are assembled. The statements inall other branches are ignored.<BR>If none of the conditions is TRUE, only the statements in the ELSE branch(if any) are assembled.</P><P><BLOCKQUOTE><STRONG><PRE>IFxx <condition 1> . ;assembled if <condition 1> is TRUE .ELSEIFxx <condition 2> . ;assembled if <condition 1> is FALSE, . ;and <condition 2> is TRUEELSEIFxx <condition 3> . ;assembled if <condition 1> and . ;<condition 2> are FALSE, and . ;<condition 3> is TRUE . .ELSEIFxx <condition n> . ;assembled if <condition 1> thru . ;<condition n-1> are FALSE and . ;<condition n> is TRUEELSE . ;assembled if <condition 1> thru . ;<condition n> are FALSEENDIF</PRE></STRONG></BLOCKQUOTE></P><P>IFxx ... ELSEIFxx ... ELSE ... ENDIF constructions may be nested to any depth!The listing mode of those constructions can be set with the $COND, $NOCOND and$CONDONLY controls.</P></BIG><!-- Seitentext Ende --><P><BR><BR><CENTER><TABLE WIDTH="70%"><TR><TH><A HREF="contents.htm"><IMG SRC="home.gif" ALT="[contents]" BORDER=0 WIDTH=32 HEIGHT=32></A></TH> <TH><A HREF="condit.htm"><IMG SRC="up.gif" ALT="[up]" BORDER=0 WIDTH=32 HEIGHT=32></A></TH> <TH><A HREF="condit.htm"><IMG SRC="back.gif" ALT="[back]" BORDER=0 WIDTH=32 HEIGHT=32></A></TH> <TH><A HREF="ifxxcon.htm"><IMG SRC="next.gif" ALT="[next]" BORDER=0 WIDTH=32 HEIGHT=32></A></TH></TR></TABLE></CENTER></P></TD></TR></TABLE></BODY></HTML>⌨️ 快捷键说明
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