The documentation on perlxs seems to say that by designating a parameter "OUTPUT:", its value may be changed in the called C function and even though it is not a traditional return value, the corresponding variable in the calling Perl script will contain the new value. I am passing a scalar through a Perl extension to a C function, where (as an integer) it is changed. When control returns to the Perl script, the value is the same as it was before the function was called. I just can't seem to get this to work.
.XS file: 
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"
#include <TestInclude.h>
MODULE = TEST        PACKAGE = TEST
        
void
C_function(iReturn)
        int           iReturn
    OUTPUT:
        iReturn

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C function: 
#include "TestInclude.h"

void C_function(int    iReturn)
{
    iReturn = 5;
}

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.H prototype:
void  C_function(int      iReturn);

.PM file: 
package TEST;

require Exporter;
require DynaLoader;
@ISA = qw(Exporter DynaLoader);
@EXPORT = qw(C_function);

bootstrap TEST;
1;

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Test Script: 
use TEST;

$Code = 25;
C_function($Code);
printf("Return Code:  %d\n", $Code);

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Please help. Thanks!! -Tim Farnsworth

In reply to Perl extension parameters by timfar

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