<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html lang="en-us" xml:lang="en-us"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <meta name="security" content="public" /> <meta name="Robots" content="index,follow" /> <meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.icra.org/ratingsv02.html" l gen true r (cz 1 lz 1 nz 1 oz 1 vz 1) "http://www.rsac.org/ratingsv01.html" l gen true r (n 0 s 0 v 0 l 0) "http://www.classify.org/safesurf/" l gen true r (SS~~000 1))' /> <meta name="DC.Type" content="concept" /> <meta name="DC.Title" content="Input and output parameters" /> <meta name="abstract" content="API parameters can be used for input or output. Some parameters contain both input and output fields; these are identified as input/output (I/O) parameters in the API parameter tables." /> <meta name="description" content="API parameters can be used for input or output. Some parameters contain both input and output fields; these are identified as input/output (I/O) parameters in the API parameter tables." /> <meta name="DC.Relation" scheme="URI" content="conParameter.htm" /> <meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" /> <meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" /> <meta name="DC.Format" content="XHTML" /> <meta name="DC.Identifier" content="conIOParm" /> <meta name="DC.Language" content="en-us" /> <!-- All rights reserved. Licensed Materials Property of IBM --> <!-- US Government Users Restricted Rights --> <!-- Use, duplication or disclosure restricted by --> <!-- GSA ADP Schedule Contract with IBM Corp. --> <link rel="stylesheet" type="text/css" href="./ibmdita.css" /> <link rel="stylesheet" type="text/css" href="./ic.css" /> <title>Input and output parameters</title> </head> <body id="conIOParm"><a name="conIOParm"><!-- --></a> <!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script> <h1 class="topictitle1">Input and output parameters</h1> <div><p>API parameters can be used for input or output. Some parameters contain both input and output fields; these are identified as input/output (I/O) parameters in the API parameter tables.</p> <p>Input parameters and fields are not changed by the API. They have the same value on the return from the API call as they do before the API call. In contrast, output parameters and fields are changed. Any information that an API caller (either an application program or an interactive entry on the display) places in an output parameter or output field before the call will be lost on the return from the call.</p> <p>Parameters can be classified into the following general categories:</p> <ul><li><em>Input parameters</em>: These parameters must be set to a value before calling the API because they pass needed information to the API to enable it to perform its function. For example, if the API is to perform a function on an object, one of the parameters would be the name and library of that object. Input parameters are not changed by the API.</li> <li><em>Output parameters</em>: These parameters do not need to be set before calling the API because the API returns information to the application in these parameters. When a return to the application is successful and no errors have occurred, the application then accesses the information returned in output parameters.</li> <li><em>Input/Output parameters</em>: These are parameters that are identified as structures that contain fields. The fields within the structure can be either input, output, or both. For example, the bytes provided field in the error code parameter is an input field. The rest of the fields that make up this parameter are output fields. The rules for input parameters and output parameters apply to the individual fields in the structure.</li> </ul> </div> <div> <div class="familylinks"> <div class="parentlink"><strong>Parent topic:</strong> <a href="conParameter.htm" title="After you have found the API that you want to use, you need to code a call to an API and pass to the API the required set of parameters appropriate for that API.">API parameters</a></div> </div> </div> </body> </html>