124 lines
6.8 KiB
HTML
124 lines
6.8 KiB
HTML
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<?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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<html lang="en-us" xml:lang="en-us">
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<meta name="DC.Type" content="task" />
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<meta name="DC.Title" content="Character length errors" />
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<meta name="abstract" content="This details errors that occur when you pass character values with incorrect length." />
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<meta name="description" content="This details errors that occur when you pass character values with incorrect length." />
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<meta name="DC.subject" content="error, character length, character length error, CALLPRC (Call Procedure) command, example, command, CL, CALLPRC (Call Procedure), calling, description, calling procedure, CALLPRC command example" />
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<meta name="keywords" content="error, character length, character length error, CALLPRC (Call Procedure) command, example, command, CL, CALLPRC (Call Procedure), calling, description, calling procedure, CALLPRC command example" />
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<meta name="DC.Relation" scheme="URI" content="comer.htm" />
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<meta name="DC.Relation" scheme="URI" content="../cl/callprc.htm" />
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<meta name="DC.Relation" scheme="URI" content="../cl/call.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" />
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Character length errors</title>
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</head>
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<body id="clerr"><a name="clerr"><!-- --></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">Character length errors</h1>
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<div><p>This details errors that occur when you pass character values with
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incorrect length.</p>
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<div class="section"> <p>If you pass a character value longer than the declared character
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length of the receiving variable, the receiving procedure or program cannot
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access the excess length. In the following example, PGMB changes the variable
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that is passed to it to blanks. Because the variable is declared with <samp class="codeph">LEN(5</samp>),
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only 5 characters are changed to blanks in PGMB, but the remaining characters
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are still part of the value when referred to in PGMA. </p>
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<pre>PGM /* PGMA */
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DCL &A *CHAR 10
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CHGVAR &A 'ABCDEFGHIJ'
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CALL PGMB PARM(&A) /* PASS to PGMB */
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.
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.
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.
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IF (&A *EQ ' ') THEN(...) /* THIS TEST FAILS */
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ENDPGM
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PGM PARM(&A) /* PGMB */
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DCL &A *CHAR 5 /* THIS LEN ERROR*/
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CHGVAR &A ' ' /* 5 POSITIONS ONLY; OTHERS UNAFFECTED */
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RETURN</pre>
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<p>While this kind of error does not cause an escape message,
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variables handled this way may function differently than expected.</p>
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<p>If
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the value passed to a procedure or program is shorter than its declared length
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in the receiving procedure or program, there may be more serious consequences.
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In this case, the value of the variable in the called procedure or program
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consists of its values as originally passed, and whatever follows that value
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in storage, up to the length declared in the called procedure or program.
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The content of this adopted storage cannot be predicted. If the passed value
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is a variable, it could be followed by other variables or by internal control
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structures for the procedure or program. If the passed value is a constant,
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it could be followed in storage by other constants passed on the CALL or CALLPRC
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command or by internal control structures.</p>
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<p>If the receiving procedure
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or program changes the value, it operates on the original value and on the
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adopted storage. The immediate effect of this could be to change other variables
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or constants, or to change internal structures in such a way that the procedure
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or program fails. Changes to the adopted storage take effect immediately.</p>
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<p>In
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the following example, two 3-character constants are passed to the called
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program. Character constants are passed with a minimum of 32 characters for
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the <span class="cmdname">Call (CALL)</span> command. (Normally, the value is passed
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as 3 characters left-adjusted with trailing blanks.) If the receiving program
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declares the receiving variable to be longer than 32 positions the extra positions
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use adopted storage of unknown value. For this example, assume that the two
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constants are adjacent in storage.</p>
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<pre>CALL PGMA ('ABC' 'DEF') /* PASSING PROG */
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PGM PARM(&A &B) /* PGMA */
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DCL &A *CHAR 50 /* VALUE:ABC+29' '+DEF+15' ' */
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DCL &B *CHAR 10 /* VALUE:DEF+7' ' */
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CHGVAR VAR(&A) (' ') /* THIS ALSO BLANKS &B */
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.
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.
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.
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ENDPGM</pre>
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<p>Values passed as variables behave in exactly the same way.</p>
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<p>In
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the following example, two 3-character constants are passed to the called
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procedure. Only the number of characters specified are passed for the <span class="cmdname">Call
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Procedure (CALLPRC)</span> command. If the receiving program
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declares the receiving variable to be longer than the length of the passed
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constant, the extra positions use adopted storage of unknown value.</p>
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<p>In
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the following example, assume the two constants are adjacent in storage.</p>
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<pre>CALLPRC PRCA ('ABC' 'DEF') /* PASSING PROG */
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PGM PARM(&A &B) /* *PRCA */
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DCL &A *CHAR 5 /* VALUE:'ABC' + 'DE' */
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DCL &B *CHAR 3 /* VALUE:'DEF' */
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CHGVAR &A ' ' /* This also blanks the first two bytes of &B */
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.
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.
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.
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ENDPGM</pre>
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</div>
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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="comer.htm" title="This describes the errors encountered most frequently in passing values on a CALL command or a CALLPRC command. Some of these errors can be very difficult to debug, and some have serious consequences for program functions.">Common errors when calling programs and procedures</a></div>
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</div>
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<div class="relinfo"><strong>Related information</strong><br />
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<div><a href="../cl/callprc.htm">Call Bound Procedure (CALLPRC) command</a></div>
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<div><a href="../cl/call.htm">Call (CALL) command</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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