How to Use mb_strstr to Find and Replace a Specific Substring in a String: Step-by-Step Guide

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<p>/*<br>
Title: How to Use mb_strstr to Find and Replace a Specific Substring in a String: Step-by-Step Guide<br>
*/</p>
<p>// When handling multibyte strings in PHP, the mbstring extension provides many useful functions.<br>
// mb_strstr is one of the functions used to find a substring. Let's go through how to use it to find and replace a specific substring in a string.</p>
<p>/*<br>
Step 1: Understanding the mb_strstr Function<br>
The basic syntax of mb_strstr is:<br>
string mb_strstr(string $haystack, string $needle, bool $before_needle = false, ?string $encoding = null)</p>
<p>Parameters:</p>
<ul>
<li>
<p>$haystack: The original string to search.</p>
</li>
<li>
<p>$needle: The substring to find.</p>
</li>
<li>
<p>$before_needle (optional): If true, returns the portion before the substring; default is false, returning the substring and everything after it.</p>
</li>
<li>
<p>$encoding (optional): String encoding, default is the internal character encoding.</p>
</li>
</ul>
<p>Return value:</p>
<ul>
<li>
<p>Returns the string (depending on $before_needle) if found.</p>
</li>
<li>
<p>Returns false if not found.<br>
*/</p>
</li>
</ul>
<p>/*<br>
Step 2: Using mb_strstr to Find a Substring<br>
Example:<br>
*/<br>
$text = "PHP is a popular server-side scripting language.";<br>
$search = "server-side";</p>
<p>$result = mb_strstr($text, $search);<br>
echo "Found substring and following content: " . $result . "\n";</p>
<p>/*<br>
Step 3: Combining with Replacement<br>
mb_strstr only finds the substring and does not replace it directly. To replace the found substring, use it together with str_replace or mb_substr.<br>
Example:<br>
*/</p>
<p>// Replace the substring with specified content<br>
$replacement = "client-side";<br>
$newText = str_replace($search, $replacement, $text);<br>
echo "Replaced string: " . $newText . "\n";</p>
<p>/*<br>
Step 4: Using mb_strstr with mb_substr for Precise Replacement (Advanced)<br>
Sometimes you need to preserve the content before and after the substring for more precise replacement:<br>
*/</p>
<p>$before = mb_strstr($text, $search, true); // Portion before the substring<br>
$after = mb_substr($text, mb_strlen($before . $search)); // Portion after the substring<br>
$finalText = $before . $replacement . $after;<br>
echo "Precisely replaced string: " . $finalText . "\n";</p>
<p>/*<br>
Step 5: Summary of Steps</p>
<ol>
<li>
<p>Use mb_strstr to find the specified substring.</p>
</li>
<li>
<p>Decide whether to get only the content before the substring.</p>
</li>
<li>
<p>Use str_replace or combine with mb_substr to perform the replacement.</p>
</li>
<li>
<p>Output or save the replaced string.</p>
</li>
<li>
<p>Pay attention to multibyte characters and ensure mbstring functions are used.</p>
</li>
</ol>
<p>Following these steps allows you to safely and efficiently find and replace a specific substring in multibyte strings.<br>
*/</p>
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