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<concept id="GUID-6CF8A41B-C2DD-5D57-A71D-6405CE08A06B" xml:lang="en"><title>Using

Signals to Handle Asynchronous Events</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>You can use signals to handle asynchronous user events. A process (program

code) can send a signal to itself that can be handled asynchronously based

on the signal handler registered for it. This provides a way to perform tasks

in parallel without any complex thread manipulation in the program code. </p>

<p>The following example code demonstrates how a program code sets a signal

to itself and how it handles the signal asynchronously in a signal handler: </p>

<codeblock id="GUID-4424321B-112A-5556-AD29-41F613A60C84" xml:space="preserve">#include &lt;signal.h&gt;

#include <stdio.h>

void sighandler(int signum)

    {

    if(signum == SIGUSR1)

        {

        // Code to perform custom handling

        }

    else if(signum == SIGUSR2)

        {

        // Code to perform custom handling

        }

    }

int main()

    {

    signal(SIGUSR1,sighandler);

    signal(SIGUSR2,sighandler);

    // program logic

    raise(SIGUSR1); // indicates user event one

    // program logic

    raise(SIGUSR2); // indicates user event two

    // program logic

    return 0;

    }</codeblock>

</conbody><related-links>

<link href="GUID-66C1493D-5B85-558A-9A39-454E6EBA307B.dita"><linktext>Signal Emulation

on the Symbian Platform</linktext></link>

<link href="GUID-186B9876-2A08-5F23-BB49-49EC34C51507.dita"><linktext>Using Signals

to Terminate Processes</linktext></link>

<link href="GUID-E65D91AE-482F-5592-B83C-0F29126C2EFA.dita"><linktext>Using Signals

to Handle Exceptions</linktext></link>