rand

(PHP 4, PHP 5)

randGenerate a random integer

Description

int rand ( void )
int rand ( int $min , int $max )

If called without the optional min, max arguments rand() returns a pseudo-random integer between 0 and getrandmax(). If you want a random number between 5 and 15 (inclusive), for example, use rand(5, 15).

Note: On some platforms (such as Windows), getrandmax() is only 32767. If you require a range larger than 32767, specifying min and max will allow you to create a range larger than this, or consider using mt_rand() instead.

Parameters

min

The lowest value to return (default: 0)

max

The highest value to return (default: getrandmax())

Return Values

A pseudo random value between min (or 0) and max (or getrandmax(), inclusive).

Changelog

Version Description
4.2.0The random number generator is seeded automatically.

Examples

Example #1 rand() example

<?php
echo rand() . "\n";
echo 
rand() . "\n";

echo 
rand(515);
?>

The above example will output something similar to:

7771
22264
11

Notes

Caution

This function does not generate cryptographically secure values, and should not be used for cryptographic purposes. If you need a cryptographically secure value, consider using openssl_random_pseudo_bytes() instead.

See Also

Коментарии

Don't forget, it's faster to use bitwise operations when you need a random number that's less than some power of two. For example,

<?php
rand
()&1;
// instead of
rand(0,1);
// for generating 0 or 1,

rand()&3;
// instead of
rand(0,3);
// for generating 0, 1, 2, or 3,

rand()&7;
// instead of
rand(0,7)
// for generating 0, 1, 2, 3, 4, 5, 6, or 7,
?>

and so on. All you're doing there is generating a default random number (so PHP doesn't have to parse any arguments) and chopping off the piece that's useful to you (using a bitwise operation which is faster than even basic math).
2005-01-21 04:23:39
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