Perl for C Programmers

How Perl Handles Variables

Suppose that instead of using a static variable for your bit array, you want to pass it a Perl scalar and let the program store its data there. To do so, you need to know a little about how Perl stores its data internally.

All Perl scalar variables are represented by the type SV defined in the perl.h file. The definition of this type is

struct sv {
    void*       sv_any;         /* pointer to something */ 
    U32         sv_refcnt;      /* how many references to us */ 
    U32         sv_flags;       /* what we are */ 
}; 
typedef struct sv SV;

The sv_any field points to the data held in the scalar. This can be a Perl string (called a byte array by C programmers) or a reference to a hash, array, code, scalar, or typeglob.

The sv_refcnt is a reference count used by Perl ...