65 lines
4.2 KiB
HTML
65 lines
4.2 KiB
HTML
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<meta name="DC.Title" content="Input and output parameters" />
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<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." />
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<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." />
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<title>Input and output parameters</title>
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</head>
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<body id="conIOParm"><a name="conIOParm"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Input and output parameters</h1>
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<div><p>API parameters can be used for input or output. Some parameters
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contain both input and output fields; these are identified as input/output
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(I/O) parameters in the API parameter tables.</p>
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<p>Input parameters and fields are not changed by the API. They have the same
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value on the return from the API call as they do before the API call. In contrast,
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output parameters and fields are changed. Any information that an API caller
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(either an application program or an interactive entry on the display) places
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in an output parameter or output field before the call will be lost on the
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return from the call.</p>
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<p>Parameters can be classified into the following general categories:</p>
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<ul><li><em>Input parameters</em>: These parameters must be set to a value before
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calling the API because they pass needed information to the API to enable
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it to perform its function. For example, if the API is to perform a function
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on an object, one of the parameters would be the name and library of that
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object. Input parameters are not changed by the API.</li>
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<li><em>Output parameters</em>: These parameters do not need to be set before
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calling the API because the API returns information to the application in
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these parameters. When a return to the application is successful and no errors
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have occurred, the application then accesses the information returned in output
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parameters.</li>
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<li><em>Input/Output parameters</em>: These are parameters that are identified
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as structures that contain fields. The fields within the structure can be
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either input, output, or both. For example, the bytes provided field in the
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error code parameter is an input field. The rest of the fields that make up
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this parameter are output fields. The rules for input parameters and output
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parameters apply to the individual fields in the structure.</li>
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</ul>
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</div>
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<div>
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<div class="familylinks">
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<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>
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</div>
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</div>
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</body>
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</html>
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