十二、chr方法
1、定义:
chr(...) chr(i) -> character Return a string of one character with ordinal i; 0 <= i < 256.
2、解释:将一个整型转换成字符即将ASCII码转换成字符
3、举例:
>>> chr(97) 'a' >>> chr(107) 'k' >>> chr(50) '2'
十三、classmethod类
1、定义:
class classmethod(object) | classmethod(function) -> method | | Convert a function to be a class method. | | A class method receives the class as implicit first argument, | just like an instance method receives the instance. | To declare a class method, use this idiom: | | class C: | def f(cls, arg1, arg2, ...): ... | f = classmethod(f) | | It can be called either on the class (e.g. C.f()) or on an instance | (e.g. C().f()). The instance is ignored except for its class. | If a class method is called for a derived class, the derived class | object is passed as the implied first argument.
2、解释:将一个函数转变成类方法,类方法与实例方法相似,是把类当作第一个默认参数。 类方法可以类或者实例调用, 其中实例的调用的时候,实例本身是被忽略的。如果一个类方法被一个子(继承)类调用,那么这个子类会被当作第一个默认参数。
3、举例:
class C: def f(cls): pass f = classmethod(f) @classmethod def f(cls): pass 以上两种方式都可以定义类方法f()
十四、cmp方法
1、定义:
cmp(...) cmp(x, y) -> integer Return negative if x<y, zero if x==y, positive if x>y.
2、解释:用于比对两个参数, 如果x<y 返回负-1, 如果x==y 返回0,如果x>y返回1
3、举例:
>>> cmp('4','2') 1 >>> cmp(6,0) 1 >>> cmp(6,6) 0 >>> cmp(6,9) -1
十五、coerce方法
1、定义:
coerce(...) coerce(x, y) -> (x1, y1) Return a tuple consisting of the two numeric arguments converted to a common type, using the same rules as used by arithmetic operations. If coercion is not possible, raise TypeError.
2、解释:通过使用相同的规则,返回两个相同常用类型的数字参数, 如果转换不可能,则抛出TypeError错误类型
3、举例:
>>> coerce(1,2) (1, 2) >>> coerce(1L,2) (1L, 2L) >>> coerce(1,2L) (1L, 2L) >>> coerce(1.0,2L) (1.0, 2.0) >>> coerce(1.0,2L) 注:复数也会做相同转换
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