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<?php var_dump( filter_var(1, FILTER_VALIDATE_BOOLEAN) ); var_dump( (1) ); var_dump( !(!1) ); echo str_repeat('-', 30); var_dump( filter_var('1', FILTER_VALIDATE_BOOLEAN) ); var_dump( filter_var(0, FILTER_VALIDATE_BOOLEAN) ); var_dump( filter_var('0', FILTER_VALIDATE_BOOLEAN) ); var_dump( filter_var(true, FILTER_VALIDATE_BOOLEAN) ); var_dump( filter_var(false, FILTER_VALIDATE_BOOLEAN) );
Output for 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 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
bool(true) int(1) bool(true) ------------------------------bool(true) bool(false) bool(false) bool(true) bool(false)

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199.47 ms | 403 KiB | 287 Q