Why Am I Getting the 'Unknown Modifier 'g' in preg_match' Error?

Unveiling the Mystery Behind "Unknown Modifier 'g' in preg_match"

When working with regular expressions in PHP using the preg_match function, you may encounter an error message stating "Unknown modifier 'g'". This issue pertains to an incorrect syntax in the regular expression you're using.

The Problem

The regular expression you're attempting to use contains the 'g' modifier (e.g., /regex/gim) which is not recognized by the preg_match function. While some online regex testing websites may allow for the 'g' modifier, PHP does not support it in this context.

The Solution

To resolve this issue, you can use the preg_match_all function instead, which does support the 'g' modifier for matching multiple occurrences of a pattern. The 'g' modifier introduces a global search, indicating that the function should iterate over the entire string and match all occurrences of the pattern.

Example

Instead of:

preg_match("/^(\w|\.|-)+?@(\w|-)+?\.\w{2,4}($|\.\w{2,4})$/gim", ....)

Use:

preg_match_all("/^(\w|\.|-)+?@(\w|-)+?\.\w{2,4}($|\.\w{2,4})$/im", ....)

By replacing the 'g' modifier with the 'm' modifier in the preg_match_all function, your code will function as intended, matching multiple occurrences of the specified email address pattern in the input string.

The above is the detailed content of Why Am I Getting the 'Unknown Modifier 'g' in preg_match' Error?. For more information, please follow other related articles on the PHP Chinese website!