无用的把戏

Table of Contents

1 PHP

<?php
function testRand($randFunction, $groupsNumber = 10, $rollsNumber = 200)
{
    $frequencies = array_fill(0, $groupsNumber, 0);
    foreach (range(1, $rollsNumber) as $ignored) {
        if ($randFunction == 'lcg_value') {
            $frequencies[$randFunction() * 10]++;
        } else {
            $frequencies[$randFunction(0, $groupsNumber - 1)]++;
        }
    }

    echo PHP_EOL, "------- results for `$randFunction` -------", PHP_EOL;
    $cum = 0;
    foreach ($frequencies as $index => $frequency) {
        $percent = $frequency * 100 / $rollsNumber;
        $cum += $percent;
        echo sprintf("%d\t|\t%4d\t%6.2f\t%6.2f", $index, $frequency, $percent, $cum), PHP_EOL;
    }
}

testRand('rand');
testRand('mt_rand');
testRand('lcg_value');
$$
...
<?php
    $a = [1,2,3];
    $b = ['a', 'b', 'c', 'd'];

    $i = 0;
    $a_len = count($a);

    $res = [];

    foreach ($b as $key => $value) {
        $k = $i < $a_len ? $i : $i % $a_len;

        $res[$a[$k]][] = $value;
        $i++;
    }

var_dump($res);

2 Mysql

137 文件权限 当你需要在一个字段中使用多个值代表不同的意思,但这些值又需要去组合代表不同的意义时,可以考虑参考文件权限的思想。 例如:你有一个类型字段type,你

CREATE TABLE `testing` (
  `id` int unsigned NOT NULL AUTO_INCREMENT,
  `room_number` int unsigned NOT NULL DEFAULT '0',
  `score` int NOT NULL,
  `node` int unsigned NOT NULL,
  PRIMARY KEY (`id`),
  KEY `room_number` (`room_number`),
  KEY `rs` (`room_number`,`score`),
  KEY `ns` (`node`,`score`)
) ENGINE=InnoDB;