2021-09-27 15:21:34 +02:00
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When using metacharacters like `\w` without the Unicode flag or when using hard-coded character classes like `[a-zA-Z]`,
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letters outside of the ASCII range, such as umlauts, accented letters, or letters from non-Latin languages, won’t be matched.
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This may cause code to incorrectly handle input containing such letters.
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To correctly handle non-ASCII input, it is recommended to use the Unicode flag `\u` or Unicode character properties like `\p{L}`.
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== Noncompliant Code Example
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2022-02-04 17:28:24 +01:00
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[source,php]
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2021-09-27 15:21:34 +02:00
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----
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preg_match("/[a-zA-Z]/", "ö"); // returns 0
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preg_match("/\w/", "ö"); // returns 0
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----
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== Compliant Solution
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2022-02-04 17:28:24 +01:00
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[source,php]
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2021-09-27 15:21:34 +02:00
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----
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preg_match("/\w/u", "ö"); // returns 1
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preg_match("/\p{L}/", "ö"); // return 1
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----
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