What is the difference between eregi_replace and preg_match_all when working with regex in PHP?

The main difference between eregi_replace and preg_match_all when working with regex in PHP is that eregi_replace is case-insensitive, while preg_match_all is case-sensitive. Therefore, if you need to perform a case-insensitive search and replace operation, eregi_replace would be the appropriate choice. On the other hand, if you need to match patterns with specific case sensitivity, preg_match_all should be used. 

// Using eregi_replace for case-insensitive search and replace
$string = "Hello, World!";
$newString = eregi_replace("hello", "Hi", $string);
echo $newString;

// Using preg_match_all for case-sensitive pattern matching
$string = "The quick brown fox jumps over the lazy dog.";
preg_match_all("/quick/i", $string, $matches);
print_r($matches);

Keywords

eregi_replace preg_match_all regex PHP difference

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