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wp_rand( int $min, int $max )

Generates a random number.

Description

Parameters

$min

(int) (Required) Lower limit for the generated number

$max

(int) (Required) Upper limit for the generated number

Return

(int) A random number between min and max

Source

File: wp-includes/pluggable.php

function wp_rand( $min = 0, $max = 0 ) {
		global $rnd_value;

		// Some misconfigured 32bit environments (Entropy PHP, for example) truncate integers larger than PHP_INT_MAX to PHP_INT_MAX rather than overflowing them to floats.
		$max_random_number = 3000000000 === 2147483647 ? (float) '4294967295' : 4294967295; // 4294967295 = 0xffffffff

		// We only handle Ints, floats are truncated to their integer value.
		$min = (int) $min;
		$max = (int) $max;

		// Use PHP's CSPRNG, or a compatible method
		static $use_random_int_functionality = true;
		if ( $use_random_int_functionality ) {
			try {
				$_max = ( 0 != $max ) ? $max : $max_random_number;
				// wp_rand() can accept arguments in either order, PHP cannot.
				$_max = max( $min, $_max );
				$_min = min( $min, $_max );
				$val  = random_int( $_min, $_max );
				if ( false !== $val ) {
					return absint( $val );
				} else {
					$use_random_int_functionality = false;
				}
			} catch ( Error $e ) {
				$use_random_int_functionality = false;
			} catch ( Exception $e ) {
				$use_random_int_functionality = false;
			}
		}

		// Reset $rnd_value after 14 uses
		// 32(md5) + 40(sha1) + 40(sha1) / 8 = 14 random numbers from $rnd_value
		if ( strlen( $rnd_value ) < 8 ) {
			if ( defined( 'WP_SETUP_CONFIG' ) ) {
				static $seed = '';
			} else {
				$seed = get_transient( 'random_seed' );
			}
			$rnd_value  = md5( uniqid( microtime() . mt_rand(), true ) . $seed );
			$rnd_value .= sha1( $rnd_value );
			$rnd_value .= sha1( $rnd_value . $seed );
			$seed       = md5( $seed . $rnd_value );
			if ( ! defined( 'WP_SETUP_CONFIG' ) && ! defined( 'WP_INSTALLING' ) ) {
				set_transient( 'random_seed', $seed );
			}
		}

		// Take the first 8 digits for our value
		$value = substr( $rnd_value, 0, 8 );

		// Strip the first eight, leaving the remainder for the next call to wp_rand().
		$rnd_value = substr( $rnd_value, 8 );

		$value = abs( hexdec( $value ) );

		// Reduce the value to be within the min - max range
		if ( $max != 0 ) {
			$value = $min + ( $max - $min + 1 ) * $value / ( $max_random_number + 1 );
		}

		return abs( intval( $value ) );
	}

Changelog

Version Description
4.4.0 Uses PHP7 random_int() or the random_compat library if available.
2.6.2 Introduced.

© 2003–2019 WordPress Foundation
Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/functions/wp_rand