Question

给定一个如下所示的数组，如何检查来自查询字符串的值是否存在于该数组中，而不使用循环等。？

我厌倦了使用in_array，但即使价值不存在，这似乎也会返回。

我需要检查alias部分中是否存在该值。

Codepad code of the same thing I posted below.

<?php
$categories = array (
    'CAT1' => array('alias' => 'mediterranean-cuisine', 'name' => 'Mediterranean Cuisine'),
    'CAT2' => array('alias' => 'asian-cuisine', 'name' => 'Asian Cuisine'),
    'CAT3' => array('alias' => 'greek-cuisine', 'name' => 'Green Cuisine')
);

$category = 'asian-cuisine';

if(in_array($category,$categories)) {
    echo 'A category with that name was not found! '.$category;
} else {
    echo 'A category was found '.$category;
}

echo '<br>';


$category = 'xxx-cuisine';

if(in_array($category,$categories)) {
    echo 'A category with that name was not found! '.$category;
} else {
    echo 'A category was found '.$category;
}
?>

Answer 1

您需要遍历数组并检查值是否存在，如此

$categories = array (
    'CAT1' => array('alias' => 'mediterranean-cuisine', 'name' => 'Mediterranean Cuisine'),
    'CAT2' => array('alias' => 'asian-cuisine', 'name' => 'Asian Cuisine'),
    'CAT3' => array('alias' => 'greek-cuisine', 'name' => 'Green Cuisine')
);

$category = 'asian-cuisine';

$found = false;
foreach($categories as $cat) {
    if($cat['alias'] == $category) {
        echo 'A category was found '.$category;
        $found = true;
        break;
    }
}

if(!$found)  {
    echo 'A category with that name was not found! '.$category;
}

Answer 2

由于您使用的是多维数组，并且您要查找的值未设置为键，因此您需要在此处使用循环。但是，如果确实想要避免循环，您可以采取一些方法。

第一个也许最有效的方法是将你要查找的别名存储在另一个数组中，但作为该数组的键：

$aliases = array(
    'mediterranean-cuisine' => 1,
    'asian-cuisine' => 1,
    'greek-cuisine' => 1
);

然后，您可以使用array_key_exists()或isset()来确定您要查找的值是否存在：

if (isset($aliases[$_GET['alias']])) {
    echo 'Found!';
}

因为数组是PHP中的哈希映射，所以这不会在内部使用实际循环，并且应该比任何基于循环的方法更有效。

替代方法可以使用数组回调/步行功能，例如array_filter()：

function alias_check($category) {
    return ($category['alias'] === $_GET['alias']);
}

$matches = array_filter($categories, 'alias_check');
if (count($matches) > 0) {
    echo 'Found!';
}

在内部，这个执行遍历数组中的每个元素，因此从技术上讲，它不会避免循环;但是，你不必自己写一个很好的。

尽管如此，最直接，最干净的方法是使用一个简单的循环：

foreach ($categories as $category) {
    if ($category['alias'] === $_GET['alias']) {
        echo 'Found';
        break;
    }
}

Answer 3

在PHP＆gt; = 5.5.0中，您可以使用array_column()来获取别名数组。

$aliases = array_column($categories, 'alias');

然后您可以使用in_array()：

$category = 'asian-cuisine';

if(in_array($category, $aliases)) {
    echo 'A category was found '.$category;
} else {
    echo 'A category with that name was not found! '.$category;
}

echo '<br>';


$category = 'xxx-cuisine';

if(in_array($category, $aliases)) {
    echo 'A category was found '.$category;
} else {
    echo 'A category with that name was not found! '.$category;
}

Answer 4

使用＆＃34; Foreach＆＃34;导航到一个数组：

<?php
$categories = array (
    'CAT1' => array('alias' => 'mediterranean-cuisine', 'name' => 'Mediterranean Cuisine'),
    'CAT2' => array('alias' => 'asian-cuisine', 'name' => 'Asian Cuisine'),
    'CAT3' => array('alias' => 'greek-cuisine', 'name' => 'Green Cuisine')
);

$category = 'asian-cuisine';

foreach($categories as $c => $k)
{
    if(in_array($category,$k))
        echo $category." founded in array ".$c."<br/>";
}

在PHP手册中查看有关Foreach的更多信息=＆gt; http://php.net/manual/en/control-structures.foreach.php

编辑：不够快=）

检查这样的php数组中是否存在值？

4 个答案: