90 lines
5.3 KiB
HTML
90 lines
5.3 KiB
HTML
<?xml version="1.0" encoding="UTF-8"?>
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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.Type" content="concept" />
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<meta name="DC.Title" content="Validity checking" />
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<meta name="abstract" content="The system performs validity checking on commands. You may also write your own validity checking program although it is not required." />
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<title>Validity checking</title>
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</head>
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<body id="valid"><a name="valid"><!-- --></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">Validity checking</h1>
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<div><p>The system performs validity checking on commands. You may also
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write your own validity checking program although it is not required.</p>
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<p>The validity checking performed by the system ensures that: </p>
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<ul><li>Values for the required parameters are entered.</li>
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<li>Each parameter value meets data type and length requirements.</li>
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<li>Each parameter value meets optional requirements specified in the command
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definition of: <ul><li>A list of valid values</li>
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<li>A range of values</li>
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<li>A relational comparison to a value</li>
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</ul>
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</li>
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<li>Conflicting parameters are not entered.</li>
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</ul>
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<p>The system performs validity checking when: </p>
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<ul><li>Commands are entered interactively from a display station.</li>
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<li>Commands are entered from a batch input stream using spooling.</li>
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<li>Commands are entered into a database file through the source entry utility
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(SEU).</li>
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<li>A command is passed to the QCMDEXC, QCMDCHK, or QCAPCMD program by a call
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from a HLL. </li>
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<li>A CL module or OPM program is created.</li>
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<li>Commands are run by a CL procedure or program or a REXX procedure.</li>
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<li>A command is run using the C language system function.</li>
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</ul>
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<p>If you need more validity checking than the system performs, you can write
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a program called a <em>validity checking program</em> or you can include the
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checking in the command processing program. You specify the names of both
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the command processing and validity checking programs on the CRTCMD command.</p>
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<p>If a command has a validity checking program, the system passes the command
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parameter values to the validity checking program. This happens before the
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system calls the command processing program. A validity checking program runs
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during syntax checking during the following conditions: </p>
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<ul><li>When running the command.</li>
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<li>When using the source entry utility (SEU) to enter commands into a CL
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source member and the programmer uses constants instead of variables for the
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parameters that are specified on the command.</li>
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<li>When compiling a CL program or procedure that uses constants instead of
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variables for all the parameters that are specified on the command.</li>
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</ul>
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<p>When the program finds an error, the user receives a message to allow immediate
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correction of errors. The command processing program can assume that the data
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that is passed to it is correct.</p>
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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="ovhdc.htm" title="This shows how a command is created.">Command definition process</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="clpgcmdAPIs.htm" title="This describes application programming interfaces (APIs) and programs that can be used when working with commands.">Use command-related APIs</a></div>
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</div>
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<div class="reltasks"><strong>Related tasks</strong><br />
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<div><a href="wvchk.htm" title="You can write a validity checking program for your command to detect errors and send diagnostic messages.">Write a validity checking program</a></div>
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</div>
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</div>
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</body>
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