"Unknown Modifier 'g' in preg_match: Unraveling the Puzzle"

When trying to utilize the powerful pattern matching capabilities of PHP's preg_match function, you might encounter an enigmatic error message: "Unknown modifier 'g'". This error arises from a lack of understanding regarding the supported modifiers.

The regex in question, aimed at validating email addresses, includes the puzzling "g" modifier, which signifies a global match. However, preg_match does not support the "g" modifier, leading to the aforementioned error. Instead, use the preg_match_all function, which is designed for global pattern matching.

To rectify this issue, simply replace "/gim" with "/im" in your regex. The "i" modifier ensures case insensitivity, while the "m" modifier enables multi-line matching.

Example:

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

By embracing this distinction, you can effectively leverage PHP's pattern matching capabilities to ensure accurate and efficient validation and extraction of information from your data.