PHP array_filter weird behavior - php

Question

I'm using array_filter with multiple parameters but it's not doing the filter correctly. Here where it's supposed to return an array with only "arts,crafts,designs" as an element, it's returning an empty array. The only $askedcat parameter it works for is "arts". I can't find out what the issue is.
I've tried not using an array_filter and instead just looping over the array, and I get the same problem.
<?php
class CategoryFilter {
public $categoryAskedFor;
function __construct($askedCat) {
$this->categoryAskedFor = $askedCat;
}
function categoryCallback($projectCategoryString) {
$project_category_array = explode(",", $projectCategoryString);
if(in_array($this->categoryAskedFor, $project_category_array)) return true;
return false;
}
}
$verifiedProjects = ["arts", "arts,crafts,designs", "film", "film,theater"];
$askedCat = "crafts";
$newArr = array_filter($verifiedProjects, array(new CategoryFilter($askedCat), "categoryCallback"));
for ($i = 0; $i < count($newArr); $i++) {
echo $newArr[$i] . "<br>";
}
I expect the output here to be arts,crafts,design<br> but it's only <br> meaning the array is empty.

Answer 1

There are many way to achieve this but let me show you two way here
WAY #1
If you using the for loop to retrieve the array value then need to have numeric key and as per your code you need array_values function to manage that
<?php
class CategoryFilter {
public $categoryAskedFor;
function __construct($askedCat) {
$this->categoryAskedFor = $askedCat;
}
function categoryCallback($projectCategoryString) {
$project_category_array = explode(",", $projectCategoryString);
if(in_array($this->categoryAskedFor, $project_category_array)) return true;
return false;
}
}
$verifiedProjects = ["arts", "arts,crafts,designs", "film", "film,theater"];
$askedCat = "crafts";
$newArr = array_filter($verifiedProjects, array(new CategoryFilter($askedCat), "categoryCallback"));
$newArr = array_values($newArr);
for ($i = 0; $i < count($newArr); $i++) {
echo $newArr[$i] . "<br>";
}
WAY # 2
If you don't want to use the array_values here then you need to manage the foreach loop instead of for loop
<?php
class CategoryFilter {
public $categoryAskedFor;
function __construct($askedCat) {
$this->categoryAskedFor = $askedCat;
}
function categoryCallback($projectCategoryString) {
$project_category_array = explode(",", $projectCategoryString);
if(in_array($this->categoryAskedFor, $project_category_array)) return true;
return false;
}
}
$verifiedProjects = ["arts", "arts,crafts,designs", "film", "film,theater"];
$askedCat = "crafts";
$newArr = array_filter($verifiedProjects, array(new CategoryFilter($askedCat), "categoryCallback"));
foreach ($newArr as $value) {
echo $value . "<br>";
}

Answer 2

The way you're looping over your resulting array is wrong, because array_filter will preserve the array keys. The 0 index may not be there in the filtered version (and in your case, it actually isn't).
Use foreach instead:
foreach ($newArr as $value) {
echo $value, '<br>';
}

Answer 3

array_filter will remove elements but will not reset the keys. use array_values to reset the keys first.
$newArr = array_values($newArr);
for ($i = 0; $i < count($newArr); $i++) {
echo $newArr[$i] . "<br>";
}

Answer 4

You will get as per your output
$askedCat = 'crafts';
$verifiedProjects = ["arts", "arts,crafts,designs", "film", "film,theater"];
$newArr = array_filter($verifiedProjects, function ($item) use ($askedCat) {
if (stripos($item, $askedCat) !== false) {
return true;
}
return false;
});
foreach ($newArr as $value) {
echo $value . "<br>";
}