Generate a unique ID

Opis

string uniqid ([ string $prefix = "" [, bool $more_entropy = false ]] )

Gets a prefixed unique identifier based on the current time in microseconds.

Parametry

prefix

Can be useful, for instance, if you generate identifiers simultaneously on several hosts that might happen to generate the identifier at the same microsecond.

With an empty prefix, the returned string will be 13 characters long. If more_entropy is TRUE, it will be 23 characters.

more_entropy

If set to TRUE, uniqid() will add additional entropy (using the combined linear congruential generator) at the end of the return value, which increases the likelihood that the result will be unique.

Zwracane wartości

Returns the unique identifier, as a string.

Przykłady

Przykład #1 uniqid() Example


<?php
/* A uniqid, like: 4b3403665fea6 */
printf("uniqid(): %s\r\n", uniqid());

/* We can also prefix the uniqid, this the same as 
 * doing:
 *
 * $uniqid = $prefix . uniqid();
 * $uniqid = uniqid($prefix);
 */
printf("uniqid('php_'): %s\r\n", uniqid('php_'));

/* We can also activate the more_entropy parameter, which is 
 * required on some systems, like Cygwin. This makes uniqid()
 * produce a value like: 4b340550242239.64159797
 */
printf("uniqid('', true): %s\r\n", uniqid('', true));
?>

Rejestr zmian

Wersja	Opis
5.0.0	The `prefix` parameter was made optional.
4.3.1	The limit of 114 characters long for `prefix` was raised.

Notatki

Uwaga

This function does not generate cryptographically secure tokens, in fact without being passed any additional parameters the return value is little different from microtime(). If you need to generate cryptographically secure tokens use openssl_random_pseudo_bytes().

Informacja:
Under Cygwin, the more_entropy must be set to TRUE for this function to work.