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

hash_initInitialize an incremental hashing context


    string $algo,
    int $flags = 0,
    string $key = "",
    array $options = []
): HashContext

Elenco dei parametri


Name of selected hashing algorithm (i.e. "md5", "sha256", "haval160,4", etc..). For a list of supported algorithms see hash_algos().


Optional settings for hash generation, currently supports only one option: HASH_HMAC. When specified, the key must be specified.


When HASH_HMAC is specified for flags, a shared secret key to be used with the HMAC hashing method must be supplied in this parameter.


An array of options for the various hashing algorithms. Currently, only the "seed" parameter is supported by the MurmurHash variants.

Valori restituiti

Returns a Hashing Context for use with hash_update(), hash_update_stream(), hash_update_file(), and hash_final().

Log delle modifiche

Versione Descrizione
8.1.0 The options parameter has been added.
7.2.0 Usage of non-cryptographic hash functions (adler32, crc32, crc32b, fnv132, fnv1a32, fnv164, fnv1a64, joaat) with HASH_HMAC was disabled.
7.2.0 Return HashContext instead of resource.


Example #1 Incremental hashing example

hash_update($ctx'The quick brown fox ');
hash_update($ctx'jumped over the lazy dog.');

Il precedente esempio visualizzerĂ :


Vedere anche:

  • hash() - Generate a hash value (message digest)
  • hash_algos() - Return a list of registered hashing algorithms
  • hash_file() - Generate a hash value using the contents of a given file
  • hash_hmac() - Generate a keyed hash value using the HMAC method
  • hash_hmac_file() - Generate a keyed hash value using the HMAC method and the contents of a given file

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