openclonk/docs/sdk/script/for.xml

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  <title>The 'for' Loop</title>
  <h>The 'for' Loop</h>
  <part>
    <text>The <code>for</code> loop is a very convenient loop with starting initialization. It is most often used as <a href="#Zaehlschleife">counting loop</a>. It will take three statements as parameters, each separated by a ';' semicolon. Followed by the code block to be executed:</text>
    <code>for([Initialisierung]; [Bedingung]; [Inkrementierung]))
  [Auszuführende Anweisung];
</code>
    <text>
      <ul>
        <li>The first statement will be executed once at the beginning of the loop. This is a good place to initialize counter variables.</li>
        <li>The second statement contains the loop condition. As soon as this condition returns 'false', the loop execution is stopped. The condition is checked before each loop execution.</li>
        <li>The third statement is executed after each loop execution. This is a good place to count up or down your counter variables.</li>
      </ul>
    </text>
    <text>It is possible to omit any of the three statements. If there is no condition statement, then the loop will run forever unless it is manually interrupted (i.e. using the <code>break</code> keyword). This is an infinite loop:</text>
    <code>for(;;)
  <funclink>Log</funclink>(&quot;Fl00d!&quot;);
</code>
    <h id="Zaehlschleife">Using for as a counting loop</h>
    <text>This is the most common use of the for loop. If, for example, you want to print all numbers from 1 to 10, you would write:</text>
    <code>for(var i = 1; i &lt;= 10; i++)
  <funclink>Log</funclink>(&quot;%d&quot;, i);
</code>
    <text>Notice: the following <funclink>while</funclink> loop would do exactly the same:</text>
    <code>var i = 0;
<funclink>while</funclink>(++i &lt;= 10)
  <funclink>Log</funclink>(&quot;%d&quot;, i);
</code>
    <h id="Arrayschleife">Using for to iterate over an array</h>
    <text>Another function of the <code>for</code>-loop is iterating over arrays. Each element of the array is stored in the variable and the loop body executed for that element. The script looks like this:</text>
    <code>for(var element in a)
  <funclink>Log</funclink>(&quot;%v&quot;, element);
</code>
    <text>This script would output all elements of the array <code>a</code> to the log.</text>
    <h>Further examples:</h>
    <code>for(var i = 10; i &gt;= 1; i--)
  <funclink>Log</funclink>(&quot;%d&quot;, i);
</code>
    <text>Counts backwards from 10 to 1.</text>
  </part>
  <author>Peter</author><date>2004-06</date>
</doc>