add#

Feed byte data into a Digest::SHA object incrementally.

Appends each argument to the running hash in order. Use add when the data does not fit comfortably in memory, when you are assembling the message from many sources, or when you want to branch the computation via clone. Calling add($a, $b, $c) is equivalent to calling add($a)->add($b)->add($c) or to calling add($a . $b . $c).

Arguments are treated as byte strings via SvPVbyte semantics: raw bytes pass straight through, UTF-8 strings are downgraded to Latin-1 bytes, and wide characters (codepoint above 255) croak.

Synopsis#

$sha->add($data);
$sha->add(@chunks);
$sha->add($a)->add($b)->add($c);

What you get back#

The receiver, so calls chain.

Examples#

my $sha = Digest::SHA->new(256);
$sha->add("abc");
print $sha->hexdigest;

## ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad

my $sha = Digest::SHA->new(512);
while (defined(my $line = <$fh>)) {
    $sha->add($line);
}
print $sha->hexdigest;

my $sha = Digest::SHA->new(256);
$sha->add("a", "b", "c");

## identical to $sha->add("abc")

Edge cases#

  • Empty strings are silently absorbed with no effect on the hash.

  • A wide character in any argument croaks with Wide character in subroutine entry; encode to UTF-8 explicitly before add if you want to hash non-Latin-1 text.

  • Called on an object that is not a Digest::SHA, returns undef.

Differences from upstream#

Fully compatible with upstream Digest::SHA 6.04.

See also#

  • addfile — feed a filehandle or filename directly, avoiding a read loop.

  • add_bits — hash a sub-byte number of bits.

  • digest — finalise and return the hash once all data is fed.