? PHP String Replace Functions

? Quick Overview

PHP provides powerful string replacement functions that allow developers to search and replace substrings easily. The most commonly used functions are str_replace() and str_ireplace().

?️ Key Concepts

• str_replace() – Case-sensitive string replacement
• str_ireplace() – Case-insensitive string replacement
• Multiple replacements supported

? Syntax / Theory

Both functions accept a search value, a replacement value, and the original string. They return a modified string without changing the original variable.

? Code Example: str_replace()

// Replace a substring in a case-sensitive way
<?php
$string = "Hello World";
$newString = str_replace("World", "PHP", $string);
echo $newString;
?>

? Live Output / Explanation

The output will be Hello PHP because the substring World is replaced with PHP.

? Code Example: str_ireplace()

// Replace a substring ignoring case sensitivity
<?php
$string = "Hello World";
$newString = str_ireplace("world", "PHP", $string);
echo $newString;
?>

? Live Output / Explanation

Even though world is lowercase, it matches World and produces Hello PHP.

? Code Example: Multiple Replacements

// Replace multiple occurrences of the same word
<?php
$string = "Hello World, welcome to the World!";
$newString = str_replace("World", "PHP", $string);
echo $newString;
?>

? Use Cases

• Cleaning user input
• Formatting dynamic text
• Replacing placeholders in templates
• Search-and-replace operations in CMS systems

? Interactive Visual Explanation