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<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Chapter 6. Программирование в GEL</title><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot"><link rel="home" href="index.html" title="Руководство пользователя Genius"><link rel="up" href="index.html" title="Руководство пользователя Genius"><link rel="prev" href="ch05s07.html" title="Список операторов GEL"><link rel="next" href="ch06s02.html" title="Циклы"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 6. Программирование в GEL</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch05s07.html">Prev</a> </td><th width="60%" align="center"> </th><td width="20%" align="right"> <a accesskey="n" href="ch06s02.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="genius-gel-programming"></a>Chapter 6. Программирование в GEL</h1></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="sect1"><a href="ch06.html#genius-gel-conditionals">Условные операторы</a></span></dt><dt><span class="sect1"><a href="ch06s02.html">Циклы</a></span></dt><dd><dl><dt><span class="sect2"><a href="ch06s02.html#genius-gel-loops-while">Циклы While</a></span></dt><dt><span class="sect2"><a href="ch06s02.html#genius-gel-loops-for">Циклы For</a></span></dt><dt><span class="sect2"><a href="ch06s02.html#genius-gel-loops-foreach">Циклы Foreach</a></span></dt><dt><span class="sect2"><a href="ch06s02.html#genius-gel-loops-break-continue">Break и Continue</a></span></dt></dl></dd><dt><span class="sect1"><a href="ch06s03.html">Суммы и произведения</a></span></dt><dt><span class="sect1"><a href="ch06s04.html">Операторы сравнения</a></span></dt><dt><span class="sect1"><a href="ch06s05.html">Глобальные переменные и область видимости переменных</a></span></dt><dt><span class="sect1"><a href="ch06s06.html">Parameter variables</a></span></dt><dt><span class="sect1"><a href="ch06s07.html">Returning</a></span></dt><dt><span class="sect1"><a href="ch06s08.html">References</a></span></dt><dt><span class="sect1"><a href="ch06s09.html">Lvalues</a></span></dt></dl></div><div class="sect1"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="genius-gel-conditionals"></a>Условные операторы</h2></div></div></div><p lang="en">
Syntax:
</p><pre lang="en" class="programlisting">if <expression1> then <expression2> [else <expression3>]
</pre><p lang="en">
If <code class="literal">else</code> is omitted, then if the <code class="literal">expression1</code> yields <code class="constant">false</code> or 0, <code class="literal">NULL</code> is returned.
</p><p lang="en">
Examples:
</p><pre lang="en" class="programlisting">if(a==5)then(a=a-1)
if b<a then b=a
if c>0 then c=c-1 else c=0
a = ( if b>0 then b else 1 )
</pre><p lang="en">
Note that <code class="literal">=</code> will be translated to <code class="literal">==</code> if used inside the expression for <code class="literal">if</code>, so
</p><pre lang="en" class="programlisting">if a=5 then a=a-1
</pre><p lang="en">
will be interpreted as:
</p><pre lang="en" class="programlisting">if a==5 then a:=a-1
</pre><p lang="en">
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