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 Copyright (c) 2000-2021 Ericsson Telecom AB
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 which accompanies this distribution, and is available at
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  Szabados, Kristof
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<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<meta http-equiv="Content-Language" content="en-us">
<title>if</title>
</head>
<body bgcolor="#DAD3C5" vlink="#0094D2" link="#003258">
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<p><br clear="all">
</p>
<hr>
<h1>if</h1>
<blockquote>
<p>1. <a href="#4.">Conditional statement with one alternative</a></p>
<p>2. <a href="#5.">Conditional statement with two alternatives</a></p>
<p>3. <a href="#5.">Conditional statement with several alternatives</a></p>
</blockquote>
<p>The conditional statement is used to branch in the program execution in function of Boolean expression. It is possible to chain more than one such branching in one program statement.</p>
<p>Related keywords:</p>
<ul>
  <li><a href="else.html"><b><font face="Courier New" color="#003258" size="4">else</font></b></a></li>
</ul>
<hr align="left" width="75%">
<h4><a name="4.">1. Conditional statement with one alternative</a></h4>
<hr align="left" width="50%">
<div align="center">
<center>
<table border="0" width="90%" bgcolor="#FFB599" cellpadding="4">
  <tr>
    <td width="100%">
    <h3 align="center"><font face="Courier New" color="#003258" size="5"><b>if(</b></font><i> condition </i><font face="Courier New" color="#003258" size="5"><b>){</b></font>&nbsp;<i>
    statement_block </i><font face="Courier New" color="#003258" size="5"><b>};</b></font></h3>
    </td>
  </tr>
</table>
</center>
</div>
<ul>
  <li>
  <p>The <font face="Courier New" color="#003258" size="4"><b>if</b></font> keyword introduces the conditional statement.</p>
  </li>
  <li>
  <p><i>condition</i> is a Boolean expression.</p>
  </li>
  <li>
  <p><i>statement_block</i> contains one or more statements. The block will only be executed if the value of the preceding logical expression (<i>condition</i>) is true.</p>
  </li>
</ul>
<p><a href="#Ex4">Example</a></p>
<hr align="left" width="75%" color="#0094D2">
<h4><a name="5.">2. Conditional statement with two alternatives</a></h4>
<hr align="left" width="50%" color="#0094D2">
<div align="center">
<center>
<table border="0" width="90%" bgcolor="#FFB599" cellpadding="4">
  <tr>
    <td width="100%">
    <h3 align="center"><font face="Courier New" color="#003258" size="5"><b>if(</b></font><i> condition </i><font face="Courier New" color="#003258" size="5"><b>){</b></font>&nbsp;<i>
    statement_block<sub>1</sub> </i><font face="Courier New" color="#003258" size="5"><b>} else {</b></font>&nbsp;<i> statement_block<sub>2</sub> </i><font face="Courier New" color="#003258" size="5"><b>};</b></font>
    </h3>
    </td>
  </tr>
</table>
</center>
</div>
<ul>
  <li>
  <p>The <font face="Courier New" color="#003258" size="4"><b>if</b></font> keyword introduces the conditional statement .</p>
  </li>
  <li>
  <p><i>condition</i> is a Boolean expression.</p>
  </li>
  <li>
  <p>The <font face="Courier New" color="#003258" size="4"><b>else</b></font> keyword precedes the statement block to be executed when the <i>condition</i> is false.</p>
  </li>
  <li>
  <p><i>statement_block<sub>1</sub></i> contains one or more statements. The block will only be executed if the value of the preceding logical expression (<i>condition</i>) is true.</p>
  </li>
  <li>
  <p><i>statement_block<sub>2</sub></i> contains one or more statements. The block will only be executed if the value of the preceding logical expression (<i>condition</i>) is false.</p>
  </li>
</ul>
<p><a href="#Ex5">Example</a></p>
<hr align="left" width="75%" color="#0094D2">
<h4><a name="5.">3. Conditional statement with several alternatives</a></h4>
<hr align="left" width="50%" color="#0094D2">
<div align="center">
<center>
<table border="0" width="90%" bgcolor="#FFB599" cellpadding="4">
  <tr>
    <td width="100%">
    <h3 align="center"><font face="Courier New" color="#003258" size="5"><b>if(</b></font><i> condition<sub>1</sub> </i><font face="Courier New" color="#003258" size="5"><b>){</b></font>&nbsp;<i>
    statement_block<sub>1</sub> </i><font face="Courier New" color="#003258" size="5"><b>} else if(</b></font><i> condition<sub>n</sub> </i><font face="Courier New" color="#003258" size="5"><b>){</b></font>&nbsp;<i>
    statement_block<sub>n</sub> </i><font face="Courier New" color="#003258" size="5"><b>} else {</b></font>&nbsp;<i> statement_block<sub>x</sub> </i><font face="Courier New" color="#003258" size="5"><b>};</b></font>
    </h3>
    </td>
  </tr>
</table>
</center>
</div>
<ul>
  <li>
  <p>The <font face="Courier New" color="#003258" size="4"><b>if</b></font> keyword introduces the conditional statement.</p>
  </li>
  <li>
  <p><i>condition<sub>1</sub></i> is a Boolean expression.</p>
  </li>
  <li>
  <p><i>statement_block<sub>1</sub></i> contains one or more statements. The block will only be executed if the value of&nbsp; <i>condition<sub>1</sub></i>&nbsp; is true.</p>
  </li>
  <li>
  <p>The <font face="Courier New" color="#003258" size="4"><b>else if</b></font> keyword pair precedes the next condition (<i>condition<sub>n</sub></i>)&nbsp; to be checked. The keyword pair and
  the following <i>condition<sub>n</sub></i> and <i>statement_block<sub>n</sub></i> may be repeated as many times as needed.</p>
  </li>
  <li>
  <p><i>condition<sub>n</sub></i> is a Boolean expression.</p>
  </li>
  <li>
  <p><i>statement_block<sub>n</sub></i> contains one or more statements. The block will only be executed if the value of&nbsp; <i>condition<sub>n</sub></i> is true AND all preceding conditions (<i>condition<sub>i</sub></i>,
  where i = 1 .. n-1) are false.</p>
  </li>
  <li>
  <p>The <font face="Courier New" color="#003258" size="4"><b>else</b></font> keyword introduces the conditional statement.</p>
  </li>
  <li>
  <p><i>statement_block<sub>x</sub></i> contains one or more statements. The block will only be executed if the value of all preceding conditions (<i>condition<sub>i</sub></i>, where i = 1 ..
  n)&nbsp; is false.</p>
  </li>
</ul>
<p><a href="#Ex3">Example</a></p>
<hr align="left" width="50%">
<p><a name="Ex4">Example 1</a>:
<p><font face="Courier New">if (v_date == &quot;1.1.2000&quot;) { log ( &quot;apage&quot; ) };</font></p>
<p>When the variable v_date equals the character string 1.1.2000, the word apage will be written to the log.</p>
<p><a name="Ex5">Example 2</a>:
<p><font face="Courier New">if (v_datum == &quot;1.1.2000&quot;) { log ( &quot;apage&quot; ) } else { log ( &quot;satanas&quot; ) };</font></p>
<p>When the variable v_datum equals the character string 1.1.2000, the word apage, else the word satanas will be written to the log.</p>
<p><a name="Ex3">Example 3</a>:
<p><font face="Courier New">if (v_data == &quot;red&quot;) { log ( &quot;rot&quot; ) } else if (v_data == &quot;blue&quot;){ log ( &quot;blau&quot; ) } else { log ( &quot;duester&quot; )
};</font></p>
<p>When the variable v_data equals the character string red, the word rot will be written to the log. .When the variable v_data equals the character string blue, the word blau will be written to
the log. When the variable v_data contains something else, the word duester will be written to the log.&nbsp;</p>
<hr align="left" width="25%">
<hr align="left" width="25%">
<p><a HREF="BNF.html#conditionalconstruct">BNF definition</a> of <font face="Courier New"> if</font></p>
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