Any object can be tested for truth value, for use in an if or while condition or as operand of the Boolean operations below. The following values are considered false: - None - False - zero of any numeric type, for example,0,0.0, 0j. - any empty sequence, for example, ”,(), []. - any empty mapping, for example, {}. - instances of user-defined classes, if the class defines a bool() or len() method, when that method returns the integer zero orbool valueFalse.
All other values are considered true — so objects of many types are always true. Operations and built-in functions that have a Boolean result always return0 orFalse for false and1 orTrue for true, unless otherwise stated. (Important exception: the Boolean operationsor andand always return one of their operands.)
任意对象可以通过‘使用 if 或 while条件’或‘在布尔预算中作为操作数’来检测真值。以下值被认为是否： - None - False - 任意数值类型的0值，例如：0, 0.0, 0j - 任意空序列，例如：‘’，[]，() - 任意空映射，例如：{} - 自定义类的实例，如果类定义了bool()或len()方法，当方法返回整数0或布尔值False
除此之外，所有其他值被认为是真，所以通常很多类型的对象为真。运算和内建函数的布尔运算结果，往往为否返回0或False，为真返回1或True（除非有其他规定）。
