Why Doesn't My PCRE Pattern Match Unicode Letters in PHP?

Decoding Unicode Letter Matching Conundrum in PCRE/PHP

A developer encountered difficulties in validating names using PCRE in PHP, specifically with non-ASCII characters like Ă or 张. Their initial pattern, "/^([p{L}'- ]) $/", failed to capture these characters, leading to the suspicion that either the pattern or input handling might be the culprit.

To clarify the issue, let's examine the pattern. p{L} is a Unicode character property shorthand for any Unicode letter. However, it requires UTF-8 mode to function correctly. By default, PHP operates in case-sensitive, non-Unicode mode.

As it turns out, the developer had neglected to specify the "u" modifier in their pattern. This modifier enables Unicode support, allowing character properties like p{L} to work as intended.

To resolve the issue, update the pattern:

$namePattern = '/^[-\' \p{L}]+$/u';

By adding the "u" modifier, the pattern will now accurately match Unicode letter characters, including those from non-ASCII alphabets, ensuring successful validation of names with characters like Ă and 张.

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