Question

I want to perform a case insensitive sub-string first appearance replacement.

I’ve tried this code :

$product_name_no_manufacturer = preg_replace("/$product_manufacturer/i","",$product_name, 1);
$product_name_no_manufacturer = trim($product_name_no_manufacturer);

but it doesn’t work in some cases.

When –

$product_name = "3M 3M LAMP 027";

$product_manufacturer = "3m";

the result I get is :

“3M LAMP 027”

But when the parameters are different –

$product_name = "A+k A+k-SP-LAMP-027";

$product_manufacturer = "A+k";

the result I get is :

“A+k A+k-SP-LAMP-027”

Why preg_replace doesn’t replace the first appearance of A+k?

Answer 1

+ is a special character in Regex (“match the preceding token once or more”), so you have to escape it. Whenever you insert a string into your Regex, escape it with preg_quote(), because it can contain special characters (leading to seemingly strange results as in this case).

$quoted = preg_quote($product_manufacturer, '/');
$product_name_no_manufacturer = preg_replace("/$quoted/i", "", $product_name, 1);