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13<title>if</title>
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18 <td width=105 height=40><a href="https://projects.eclipse.org/projects/tools.titan"><img src="../images/titan_transparent.gif" border=0 width=105 height=40 align="left" alt="Titan"></a></td>
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28</table>
29<p><br clear="all">
30</p>
31<hr>
32<h1>if</h1>
33<blockquote>
34<p>1. <a href="#4.">Conditional statement with one alternative</a></p>
35<p>2. <a href="#5.">Conditional statement with two alternatives</a></p>
36<p>3. <a href="#5.">Conditional statement with several alternatives</a></p>
37</blockquote>
38<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>
39<p>Related keywords:</p>
40<ul>
41 <li><a href="else.html"><b><font face="Courier New" color="#003258" size="4">else</font></b></a></li>
42</ul>
43<hr align="left" width="75%">
44<h4><a name="4.">1. Conditional statement with one alternative</a></h4>
45<hr align="left" width="50%">
46<div align="center">
47<center>
48<table border="0" width="90%" bgcolor="#FFB599" cellpadding="4">
49 <tr>
50 <td width="100%">
51 <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>
52 statement_block </i><font face="Courier New" color="#003258" size="5"><b>};</b></font></h3>
53 </td>
54 </tr>
55</table>
56</center>
57</div>
58<ul>
59 <li>
60 <p>The <font face="Courier New" color="#003258" size="4"><b>if</b></font> keyword introduces the conditional statement.</p>
61 </li>
62 <li>
63 <p><i>condition</i> is a Boolean expression.</p>
64 </li>
65 <li>
66 <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>
67 </li>
68</ul>
69<p><a href="#Ex4">Example</a></p>
70<hr align="left" width="75%" color="#0094D2">
71<h4><a name="5.">2. Conditional statement with two alternatives</a></h4>
72<hr align="left" width="50%" color="#0094D2">
73<div align="center">
74<center>
75<table border="0" width="90%" bgcolor="#FFB599" cellpadding="4">
76 <tr>
77 <td width="100%">
78 <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>
79 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>
80 </h3>
81 </td>
82 </tr>
83</table>
84</center>
85</div>
86<ul>
87 <li>
88 <p>The <font face="Courier New" color="#003258" size="4"><b>if</b></font> keyword introduces the conditional statement .</p>
89 </li>
90 <li>
91 <p><i>condition</i> is a Boolean expression.</p>
92 </li>
93 <li>
94 <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>
95 </li>
96 <li>
97 <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>
98 </li>
99 <li>
100 <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>
101 </li>
102</ul>
103<p><a href="#Ex5">Example</a></p>
104<hr align="left" width="75%" color="#0094D2">
105<h4><a name="5.">3. Conditional statement with several alternatives</a></h4>
106<hr align="left" width="50%" color="#0094D2">
107<div align="center">
108<center>
109<table border="0" width="90%" bgcolor="#FFB599" cellpadding="4">
110 <tr>
111 <td width="100%">
112 <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>
113 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>
114 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>
115 </h3>
116 </td>
117 </tr>
118</table>
119</center>
120</div>
121<ul>
122 <li>
123 <p>The <font face="Courier New" color="#003258" size="4"><b>if</b></font> keyword introduces the conditional statement.</p>
124 </li>
125 <li>
126 <p><i>condition<sub>1</sub></i> is a Boolean expression.</p>
127 </li>
128 <li>
129 <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>
130 </li>
131 <li>
132 <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
133 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>
134 </li>
135 <li>
136 <p><i>condition<sub>n</sub></i> is a Boolean expression.</p>
137 </li>
138 <li>
139 <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>,
140 where i = 1 .. n-1) are false.</p>
141 </li>
142 <li>
143 <p>The <font face="Courier New" color="#003258" size="4"><b>else</b></font> keyword introduces the conditional statement.</p>
144 </li>
145 <li>
146 <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 ..
147 n)&nbsp; is false.</p>
148 </li>
149</ul>
150<p><a href="#Ex3">Example</a></p>
151<hr align="left" width="50%">
152<p><a name="Ex4">Example 1</a>:
153<p><font face="Courier New">if (v_date == &quot;1.1.2000&quot;) { log ( &quot;apage&quot; ) };</font></p>
154<p>When the variable v_date equals the character string 1.1.2000, the word apage will be written to the log.</p>
155<p><a name="Ex5">Example 2</a>:
156<p><font face="Courier New">if (v_datum == &quot;1.1.2000&quot;) { log ( &quot;apage&quot; ) } else { log ( &quot;satanas&quot; ) };</font></p>
157<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>
158<p><a name="Ex3">Example 3</a>:
159<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; )
160};</font></p>
161<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
162the log. When the variable v_data contains something else, the word duester will be written to the log.&nbsp;</p>
163<hr align="left" width="25%">
164<hr align="left" width="25%">
165<p><a HREF="BNF.html#conditionalconstruct">BNF definition</a> of <font face="Courier New"> if</font></p>
166</body>
167</html>
Titan Core - Deliverables
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