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  2. Give it a try at least... – Kerrek SB. Sep 28, 2011 at 13:20. 1. "true" and "false" were introduced as macros with C99. true evaluates to 1 and false to 0, so true+false = 1+0 = 1 (== true), I'm not sure if true+true is valid. As that's 1+1, which is no valid value for _Bool. But don't have the standard at hand. – johannes.

  3. javascript - Why does `false && true - Stack Overflow

    stackoverflow.com/questions/21345748

    In your example: false && true || true, the false is the left expression and the first true is the right expression. The following || true is not part of the what the && operator will evaluate. The short-circuit is meant to not waste cycles evaluating the right expression, if it can no longer effect the result of the logical operator.

  4. C++ mandates that when converting bool to integral types true evaluates to 1 and false evaluates to 0, and from integral/float types it says that a zero-Value, soo 0 and -0 evaluate to false, all other values evaluàte to true. bool is an integral type but not an integer. Internally a compiler might decide to use the value 3 for false and 64 ...

  5. 1. the && operator has a left-to-right associativity. means if the first value is truthy (coercible to true) it will evaluate the second, if the second is truthy the third..until the last one that will be the result of the expression. since the first element of the operator is falsy (coercible to false) the expression returns immediatly false.

  6. 13. && (logical AND) Description :- Compares two expressions and returns true only if both evaluate to true. Returns false if one or both evaluate to false. The following list shows all possible combinations: true && false = false // Evaluates false because the second is false. false && true = false // Evaluates false because the first is false.

  7. The expression '/bla/bla/bla' will be treated as true where a Boolean expression is expected (like in an if statement), but the expressions '/bla/bla/bla' is True and '/bla/bla/bla' == True will evaluate to False for the reasons in Ignacio's answer. +1 I think this is the underlaying misunderstanding.

  8. 2 * 3 is evaluated first, and then 1 is added to the result. * has higher precedence than +, thus that operation is evaluated first. Now, lets transition to boolean expressions: (&& = AND, || = OR) true AND false OR true. C++ gives AND a higher precedence than OR, thus. (true AND false) OR true.

  9. NOTE: I am aware of Python booleans - if x:, vs if x == True, vs if x is True. However, it only addresses whether if foo, if foo == True, or if foo is True should generally be used to determine whether foo has a true-like value. UPDATE: According to PEP 285 § Specification: The values False and True will be singletons, like None. python. boolean.

  10. This solution will gurantee you always get a bool type with value True or False. (This solution has a constraint: your option must have a default value.) Here is a one-liner interpretation of @Maxim's answer parser.add_argument('--feature', dest='feature', type=lambda x:bool(distutils.util.strtobool(x))).

  11. As far as I can see, there are three ways to use Booleans in C: with the bool type, from <stdbool.h> then using true and false. defining using preprocessor #define FALSE 0 ... #define TRUE !(FALSE) Just to use constants directly, i.e. 1 and 0.