PHPの挙動メモ

自分用で、挙動確認とかしたやつのメモ。

array_intersect

https://3v4l.org/8ig5r

<?php
$a = [1,2,2,3,3,3,4,4,4,4];
$b = [2,3,5];

var_dump(
    array_intersect($a, $b), // [2,2,3,3,3] 
    array_intersect($b, $a)  // [2,3]
);

filter_

<?php
var_dump(filter_var_array(
    ['a' => 0],
    [
        'a' => [
            'filter' => FILTER_VALIDATE_INT,
            'options' => [
                'default' => 1,
                'min_range' => 1
            ],
        ],
        'b' => [
            'filter' => FILTER_VALIDATE_INT,
            'options' => [
                'default' => 0,
                'min_range' => 0,
            ],
        ],
    ]
));
/*
array(2) {
  ["a"]=>
  int(1)
  ["b"]=>
  NULL
}
*/

if文の式が、代入の式

https://3v4l.org/v4TYG

<?php

if ($t = true) { // 入る
    echo 'true assignment '.PHP_EOL;
}
if ($f = false) {
    echo 'false assignment'.PHP_EOL;
}
if ($zeroString = '0') {
    echo 'string "0" letter '.PHP_EOL;
}
if ($zeroAStringCastToInt = (int)'0a') {
    echo 'cast to int witch string "0a"'.PHP_EOL;
}
if ($zeroA = '0a') { // 入る
    echo 'string "0a" letters'.PHP_EOL;
}
if ($oneAStringCastToInt = (int)'1a') { // 入る
    echo 'cast to int witch string "1a"'.PHP_EOL;
}