Programming Perl in C

SV *sv = newSVpv("foo", 0);

av_unshift(av, 1);         // unshift(@av, undef);

av_store(av, 0, sv);       // $av[0] = "foo";

It's a bit more work, but the result is identical to Perl's unshift built in.

Deletion

An entire AV can be cleared with the av_clear() function:

av_clear(av); // @av = ();

or you can use it to clear just a single element:

av_delete(av, 9, 0); // delete the tenth element (the last arg is ignored)

Hash Values (HV)

Perl's hashes are represented in the Perl API as HVs. The HV type is the most compli 

cated of the Perl data types, and it has many more functions and macros associated 

with it than can be described here. I'll give you a subset of the available functions 

that will let you do most of what you'll need to do with hashes. In particular, I've 

avoided discussing the HE type that combines keys and values in one structure. For 

these functions, see the perlapi documentation.

Creation

HVs have a single constructor, newHV():

HV *hv = newHV();

Fetching Values

The simplest way to fetch values from a hash is with hv_fetch():

SV **svp;

// fetch $hv{foo} (last arg indicates lvalue status)

svp = hv_fetch(hv, "foo", strlen("foo"), 0);

if (!svp) croak("fetch failed: hv does not contain value for key foo");

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