note 24806 deleted from language.types.boolean by jmcastagnetto

Despite 1 and 2 can both be converted to a boolean as TRUE, they differ: (1 == TRUE) will be true (2 == TRUE) will be false! In an expression with ==, where there's a numeric value and a boolean, the boolean is promoted to the numeric type and the values are compared. So never perform tests based on the equivalent numeric value of TRUE. Don't write: if ($variable == TRUE)... as the condition would be false if the variable contains something else than a TRUE boolean, or a numeric value different of 1. Simply write: if ($variable)... or: if (!empty($variable))...