random_int( int $min, int $max )
Fetch a random integer between $min and $max inclusive
Description Description
Parameters Parameters
- $min
-
(int) (Required)
- $max
-
(int) (Required)
Return Return
(int)
Source Source
File: wp-includes/random_compat/random_int.php
41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 | function random_int( $min , $max ) { /** * Type and input logic checks * * If you pass it a float in the range (~PHP_INT_MAX, PHP_INT_MAX) * (non-inclusive), it will sanely cast it to an int. If you it's equal to * ~PHP_INT_MAX or PHP_INT_MAX, we let it fail as not an integer. Floats * lose precision, so the <= and => operators might accidentally let a float * through. */ try { $min = RandomCompat_intval( $min ); } catch (TypeError $ex ) { throw new TypeError( 'random_int(): $min must be an integer' ); } try { $max = RandomCompat_intval( $max ); } catch (TypeError $ex ) { throw new TypeError( 'random_int(): $max must be an integer' ); } /** * Now that we've verified our weak typing system has given us an integer, * let's validate the logic then we can move forward with generating random * integers along a given range. */ if ( $min > $max ) { throw new Error( 'Minimum value must be less than or equal to the maximum value' ); } if ( $max === $min ) { return (int) $min ; } /** * Initialize variables to 0 * * We want to store: * $bytes => the number of random bytes we need * $mask => an integer bitmask (for use with the &) operator * so we can minimize the number of discards */ $attempts = $bits = $bytes = $mask = $valueShift = 0; /** * At this point, $range is a positive number greater than 0. It might * overflow, however, if $max - $min > PHP_INT_MAX. PHP will cast it to * a float and we will lose some precision. */ $range = $max - $min ; /** * Test for integer overflow: */ if (! is_int ( $range )) { /** * Still safely calculate wider ranges. * Provided by @CodesInChaos, @oittaa * * * We use ~0 as a mask in this case because it generates all 1s * * @ref https://eval.in/400356 (32-bit) * @ref http://3v4l.org/XX9r5 (64-bit) */ $bytes = PHP_INT_SIZE; $mask = ~0; } else { /** * $bits is effectively ceil(log($range, 2)) without dealing with * type juggling */ while ( $range > 0) { if ( $bits % 8 === 0) { ++ $bytes ; } ++ $bits ; $range >>= 1; $mask = $mask << 1 | 1; } $valueShift = $min ; } $val = 0; /** * Now that we have our parameters set up, let's begin generating * random integers until one falls between $min and $max */ do { /** * The rejection probability is at most 0.5, so this corresponds * to a failure probability of 2^-128 for a working RNG */ if ( $attempts > 128) { throw new Exception( 'random_int: RNG is broken - too many rejections' ); } /** * Let's grab the necessary number of random bytes */ $randomByteString = random_bytes( $bytes ); /** * Let's turn $randomByteString into an integer * * This uses bitwise operators (<< and |) to build an integer * out of the values extracted from ord() * * Example: [9F] | [6D] | [32] | [0C] => * 159 + 27904 + 3276800 + 201326592 => * 204631455 */ $val &= 0; for ( $i = 0; $i < $bytes ; ++ $i ) { $val |= ord( $randomByteString [ $i ]) << ( $i * 8); } /** * Apply mask */ $val &= $mask ; $val += $valueShift ; ++ $attempts ; /** * If $val overflows to a floating point number, * ... or is larger than $max, * ... or smaller than $min, * then try again. */ } while (! is_int ( $val ) || $val > $max || $val < $min ); return (int) $val ; } |
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