1 <?xml version="1.0" encoding="utf-8"?>

     2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

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     7     Nokia Corporation - initial contribution.

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    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept xml:lang="en" id="GUID-E65D91AE-482F-5592-B83C-0F29126C2EFA"><title>Using Signals to Handle Exceptions </title><prolog><metadata><keywords/></metadata></prolog><conbody><p>Signals provide an alternative method (to checking return values) of handling exceptions or failures. The following example code demonstrates how you can check the return value for a failure and also how you can register a handler for handling the failure asynchronously: </p> <codeblock id="GUID-49B4A39A-34F5-54D1-AD97-5AD50EFD9786" xml:space="preserve">#include &lt;signal.h&gt;

    13 #include <stdio.h>

    14 int func()

    15     {

    16     int success = 1;

    17     // function logic

    18     // success == 1  - Indicates that the function logic succeeded

    19     // success == 0  - Indicates that the function logic failed

    20     if(success)

    21         return 0;

    22     else

    23         {

    24         raise(SIGUSR1);

    25         return -1;

    26         }

    27     }

    28 void sighandler(int signum)

    29     {

    30     if(signum == SIGUSR1)

    31         // 'signal' method for checking failure

    32         printf(“Error: An error occured in func().”);

    33     else

    34         printf(“Error: Unknown signal”);

    35     }

    36 int main(void)

    37     {

    38     int retval = 0;

    39     // When SIGUSR1 arrives, invoke sighandler()

    40     signal(SIGUSR1,sighandler);

    41     retval = func();

    42     if(retval == -1)

    43         // The return value method used for checking failure

    44         printf("Error: An error occured in func().");  

    45     }</codeblock> </conbody><related-links><link href="GUID-66C1493D-5B85-558A-9A39-454E6EBA307B.dita"><linktext>Signal Emulation on Symbian

    46                 Platform</linktext> </link> <link href="GUID-186B9876-2A08-5F23-BB49-49EC34C51507.dita"><linktext>Using Signals to Terminate Processes</linktext> </link> <link href="GUID-6CF8A41B-C2DD-5D57-A71D-6405CE08A06B.dita"><linktext>Using Signals to Handle Asynchronous

    47                 Events</linktext> </link> </related-links></concept>