(PHP 5 >= 5.1.2, PHP 7, PHP 8, PECL hash >= 1.1)

hash_updatePump data into an active hashing context


hash_update(HashContext $context, string $data): bool

Elenco dei parametri


Hashing context returned by hash_init().


Message to be included in the hash digest.

Valori restituiti

Returns true.

Log delle modifiche

Versione Descrizione
7.2.0 Accept HashContext instead of resource.

Vedere anche:

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User Contributed Notes 1 note

16 years ago
A simple example on incremental file hashing:

$fp = fopen($file, "r");
$ctx = hash_init('sha256');
while (!feof($fp)) {
    $buffer = fgets($fp, 65536);
    hash_update($ctx, $buffer);
$hash = hash_final($ctx, true);

While incremental hashing is quite slow, it's the easiest way to hash
- parts of large files: I.e., a 700MB avi video uses first x bytes to store metadata, so in order to hash the avi's data only, you have to fseek to data start and use incremental hashing
- streaming data if php just proxies the data
- whenever it's inadequate or impossible to store the data being hashed into memory (i.e. because of their size) or on disc.
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