Here's a little program illustrating one way of using undef as a 'NULL pointer' parameter in Inline C. 

use strict;
use warnings;

my $point = pack 'f2', 1.2, 2.3;
func(\$point); 
func(undef);   # pass in 'NULL pointer' 

use Inline C => <<'C_END';

typedef struct { float x, y; } Point;

void func(SV *buf) {
    SV *point_ref = SvRV(buf);
    
    if (!point_ref) {
        printf("got a null pointer\n");
    }
    else {
        /* dereference */
        Point *point = (Point *)SvPV_nolen(point_ref);
        printf("x=%.2f, y=%.2f\n", point->x, point->y);
    }
}

C_END

[download]

Hope this helps.

In reply to Re: Inline::C and NULL pointers by Chrysotoxum
in thread Inline::C and NULL pointers by markong

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