rand

Synopsis

Returns

Random integer

Description

The rand() function returns a random integer between zero and the maximum random value for the system, which you can determine by using getrandmax() . Optional arguments can be used to limit the range of the returned value, as long as rmax is less than or equal to the value returned by getrandmax() . To maximize the randomness of the returned value, it's always a good idea - but not essential - to seed the random number generator using srand() . If one argument is passed, both arguments must be passed; otherwise, the call will generate a warning.

Note that the mt_rand() function, which uses the Mersenne Twister algorithm to generate random numbers, is usually preferable - it's faster and has known characteristics.

Version

PHP 3, PHP 4

See also

See also getrandmax() , mt_getrandmax() , mt_rand() , mt_srand() , srand()

Example

$x = 0;
srand(mktime());  
for ($i=0; $i <= 10; $i++) {
   $rand = rand(1, 21); // return a number from 1 to 21
   $rand2 = rand();     // return a number from 0 to RAND_MAX
   $x = $x + $rand;
   echo "\$rand = $rand<BR>\n";
}
echo "Value of \$x: $x";