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<concept id="GUID-BE893F87-E7F6-56E5-BD27-328B532F8332" xml:lang="en"><title>Hello World Example: Using P.I.P.S.</title><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>This example application shows a simple EXE and DLL written using

P.I.P.S. (P.I.P.S. Is POSIX on Symbian Platform). It also shows the

dynamic lookup of symbols by name mechanism used in Unix-like operating

systems, instead of the native Symbian Platform lookup by ordinal

mechanism. P.I.P.S., from Symbian OS v9.3, provides APIs from <filepath>libdl</filepath> library to implement this lookup by name mechanism. </p>

<p>The example defines a simple DLL using the P.I.P.S. <codeph>STDDLL</codeph> target type, with an exported function. It also creates a simple

EXE, using the <codeph>STDEXE</codeph> target type, which calls the

DLL's exported function using the lookup by name mechanism. These

P.I.P.S. specific target types are required to enable the specific

options for compilers and linkers to generate P.I.P.S. executables

and to make symbol information available in the executable image. </p>

<section id="GUID-F39633E1-9E29-45BA-9F11-66E011B16687"><title>Download</title> <p>Click on the following link to

download the example: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/zips/guid-42af5ea2-87c6-46ef-b872-af35876c73c7.zip" scope="external">HelloWorldExample.zip</xref></p><p>Click: <xref href="guid-6013a680-57f9-415b-8851-c4fa63356636/guid-42af5ea2-87c6-46ef-b872-af35876c73c7.html" scope="peer">browse</xref> to view the example code. </p> </section>

<section id="GUID-459D68E3-EC28-4F21-858A-10678A443EEE"><title>Description</title> <p>The following sections provide

more information about the example. </p> <p><b> Creating a simple

DLL using P.I.P.S. STDDLL target type</b> </p> <p>The example creates

a DLL file that declares and defines an exported function. The target

type of this DLL file is <codeph>STDDLL</codeph>. It contains a header

and a source file: </p> <ul>

<li id="GUID-A0857840-AD8C-5313-A642-801A79382855"><p> <filepath>helloworlddllexample.h</filepath>: this declares a function with external linkage. Note that for a <codeph>STDDLL</codeph> library, functions and data with external linkage

are exported by default, without any requirement for <codeph>IMPORT_C</codeph> and <codeph>EXPORT_C</codeph> declarations in header or source files. </p> </li>

<li id="GUID-973CE8AE-5B87-5234-8145-20A6632E7F9C"><p> <filepath>helloworlddllexample.cpp</filepath>: this defines the function declared in the header file, which displays

a hello world message to the console. </p> </li>

</ul> <p><b> Creating a simple EXE using P.I.P.S. STDEXE target type</b> </p> <p>The example creates an EXE file which calls the exported

function of the loaded DLL. The target type of this EXE file is <codeph>STDEXE</codeph>. It calls the following <filepath>libdl</filepath> functions to use the lookup by name mechanism: </p> <ul>

<li id="GUID-08422DA9-EE4F-502C-8D31-EB19BC86F98B"><p> <xref href="GUID-51FB35C0-CFC2-357A-8ACA-FE7480C53AD3.dita"><apiname>dlopen()</apiname></xref>: This function is used to load the DLL file which contains an exported

function. </p> </li>

</ul> <ul>

<li id="GUID-0EC17FCA-7B6A-5FBF-8693-1C4BD629F553"><p> <xref href="GUID-312604D7-59D9-3C67-9D4F-42CFA24EAA2B.dita"><apiname>dlsysm()</apiname></xref>: This function gets the address of a symbol defined within the DLL

loaded by the <codeph>dlopen()</codeph> call. </p> </li>

</ul> <ul>

<li id="GUID-EFC5BA53-F378-5D2B-A550-1055DA8CBAD7"><p> <xref href="GUID-F74DC7CB-1E3F-368E-99A7-DD4B38FF7EF0.dita"><apiname>dlclose()</apiname></xref>: This function informs the system that the DLL loaded by a previous <codeph>dlopen()</codeph> call is no longer needed by the application. </p> </li>

</ul> <ul>

<li id="GUID-B6003F4A-8919-5D15-844E-294A9020A2C2"><p> <xref href="GUID-F5B2CFAB-99F5-3A24-8F6C-ECAA61922FB0.dita"><apiname>dlerror()</apiname></xref>: This function is used to get the last error that occurred from

any of the <filepath>libdl</filepath> APIs. </p> </li>

</ul> <p>The EXE links to <filepath>libdl.lib</filepath> to use these

functions. </p> </section>

<section id="GUID-15EDF774-BC24-4BD5-A185-697DCFDCF732"><title>Build</title> <p>The <filepath>HelloWorldExample</filepath> builds two files, a DLL file <filepath>helloworlddllexample.dll</filepath>, and an EXE file <filepath>helloworldexeexample.exe</filepath>,

in the standard locations. </p> <p>To run the example, start <filepath>helloworldexeexample.exe</filepath> from the file system or from

your IDE. After launching the executable, depending on the emulator

you are using, you may need to navigate away from the application

launcher or shell screen to view the console. </p> </section>