php - 数组中具有相同值的键

Question

有一次我在一次采访中被问到一个问题。下面是问题：

$arry= array("1"=>"20", "2"=>"20", "3"=>"30", "4"=>"40" "5"=>"20");

我被要求通过使用 foreach 循环找到具有相同值的键。

我仍然不知道这个问题的解决方案。有什么帮助吗？？

Answer 1

$arry= array("1"=>"20", "2"=>"20", "3"=>"30", "4"=>"40", "5"=>"20");

$results = array(); 
foreach($arry as $key=>$value) {
    $results[$value][] = $key;
}

var_dump($results);

Answer 2

在这里查看结果

<?php
$arry= array("1"=>"20", "2"=>"20", "3"=>"30", "4"=>"40","5"=>"20");

$list = array();
foreach ($arry as $key => $value)
{
    if (!isset($list[$value]))
    {
        $list[$value] = array();
    }

    $list[$value][] = $key;
}
var_export($list);

Answer 3

$arry= array("1"=>"20", "2"=>"20", "3"=>"30", "4"=>"40", "5"=>"20");
$newArr = array();
foreach($arry as $key => $val) {
    if(!array_key_exists($val, $newArr)) $newArr[$val] = "";
    $newArr[$val] .=  " - " . $key;
}

var_dump($newArr);

输出：VALUES => KEYS_WITH_SAME_VALUES

array (size=3)
20 => string ' - 1 - 2 - 5' (length=12)
30 => string ' - 3' (length=4)
40 => string ' - 4' (length=4)

Answer 4

foreach ($arry as $key=>$value) {
    if ($value == $findValue)
        print $key.' ';
}

示例$findValue为 20，则此代码打印1 2 5

Answer 5

最简单的方法：

<?php
$array = array("1"=>"20", "2"=>"20", "3"=>"30", "4"=>"40" ,"5"=>"20");
print_r(array_count_values($array));
?>

使用 foreach ：

<?php
$array = array("1"=>"20", "2"=>"20", "3"=>"30", "4"=>"40" ,"5"=>"20");
$result = array();
foreach($array as $value) {
    $result[$value]++;
}
print_r($result);
?>

在这里试一试