PHP: hash_update - Manual

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Last updated: Fri, 26 Jan 2007

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# hash_update

(no version information, might be only in CVS)

hash_update -- Pump data into an active hashing context

## Описание

bool hash_update ( resource context, string data )

## Список параметров

`context`

  Hashing context returned by hash_init().

`data`

  Message to be included in the hash digest.

## Возвращаемые значения

Returns `TRUE`.

## Смотрите также

hash_init()
hash_update_file()
hash_update_stream()
hash_final()

add a note User Contributed Notes
hash_update
Dainichi
24-Jul-2006 06:19
`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);
fclose($fp);
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.`
add a note
hash hash_update_stream

Last updated: Fri, 26 Jan 2007
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