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<?php var_dump(filter_var(null, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE)); var_dump(filter_var(false, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE)); var_dump(filter_var(true, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE)); var_dump(filter_var('test', FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE));
Output for 5.4.8 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.26, 8.0.0 - 8.0.13, 8.1rc1 - rc3
bool(false) bool(false) bool(true) NULL
Output for 5.4.0 - 5.4.7
NULL NULL bool(true) NULL

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