How to Combine array_udiff_assoc and array_map in PHP for Precise Array Element Comparison

<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// This part is unrelated to the article and can include any PHP comments or simple variable definitions</span></span><span>
</span><span><span class="hljs-variable">$dummy</span></span><span> = </span><span><span class="hljs-string">"This is preliminary unrelated code"</span></span><span>;
</span><span><span class="hljs-function"><span class="hljs-keyword">function</span></span></span><span> </span><span><span class="hljs-title">placeholderFunction</span></span><span>(</span><span><span class="hljs-params"></span></span><span>) {
    </span><span><span class="hljs-keyword">return</span></span><span> </span><span><span class="hljs-string">"Placeholder function output"</span></span><span>;
}
<p></span>?></p>
<p><hr></p>
<p><?php<br>
/**</p>
<ul>
<li>
<p>How to Combine array_udiff_assoc and array_map in PHP for Precise Array Element Comparison</p>
</li>
<li></li>
<li>
<p>In PHP, when we need to compare elements of two arrays while considering keys, values, and custom comparison logic,</p>
</li>
<li>
<p>array_udiff_assoc and array_map are two very useful tools. This article explains in detail how to combine them to achieve precise array element comparison.</p>
</li>
<li></li>
<li>
<ol>
<li>
<p>Introduction to array_udiff_assoc</p>
</li>
</ol>
</li>
<li>
<p>array_udiff_assoc() compares differences between two arrays while considering both keys and values. Its function signature is:</p>
</li>
<li></li>
<li>
<p>array_udiff_assoc(array $array1, array $array2, callable $value_compare_func): array</p>
</li>
<li></li>
<li>
<p>Here, $value_compare_func is a callback function used to define custom value comparison logic.</p>
</li>
<li></li>
<li>
<ol start="2">
<li>
<p>Introduction to array_map</p>
</li>
</ol>
</li>
<li>
<p>array_map() applies a callback function to each element of an array, producing a new array. Its signature is:</p>
</li>
<li></li>
<li>
<p>array_map(callable $callback, array ...$arrays): array</p>
</li>
<li></li>
<li>
<p>With array_map, we can normalize array elements before comparison (e.g., trimming spaces, converting to lowercase, etc.).</p>
</li>
<li></li>
<li>
<ol start="3">
<li>
<p>Combining the two</p>
</li>
</ol>
</li>
<li>
<ul>
<li>
<p>Use array_map to standardize both arrays so that element formats are consistent.</p>
</li>
</ul>
</li>
<li>
<ul>
<li>
<p>Then use array_udiff_assoc to compare the arrays, leveraging a custom callback for more precise difference detection.</p>
</li>
</ul>
</li>
<li></li>
<li>
<p>Example code:<br>
*/</p>
</li>
</ul>
<p>// Original arrays<br>
$array1 = [<br>
'a' => ' Apple ',<br>
'b' => 'Banana',<br>
'c' => 'Cherry'<br>
];</p>
<p>$array2 = [<br>
'a' => 'apple',<br>
'b' => 'banana ',<br>
'd' => 'Date'<br>
];</p>
<p>// Normalize array elements (trim and convert to lowercase)<br>
$normalizedArray1 = array_map(function($value) {<br>
return strtolower(trim($value));<br>
}, $array1);</p>
<p>$normalizedArray2 = array_map(function($value) {<br>
return strtolower(trim($value));<br>
}, $array2);</p>
<p>// Custom comparison function<br>
function compareValues($value1, $value2) {<br>
return strcmp($value1, $value2);<br>
}</p>
<p>// Use array_udiff_assoc to get elements in $array1 that differ from $array2<br>
$difference = array_udiff_assoc($normalizedArray1, $normalizedArray2, 'compareValues');</p>
<p>echo "Elements differing between the two arrays after precise comparison:\n";<br>
print_r($difference);</p>
<p>/**</p>
<ul data-is-last-node="" data-is-only-node="">
<li>
<p>Output:</p>
</li>
<li>
<p>Array</p>
</li>
<li>
<p>(</p>
</li>
<li>