Python built-in function isinstance usage and differences from type

Isinstance is an intrinsic function syntax in Python: Isinstance (object, ClassInfo) If the argument object is an instance of ClassInfo, or object is an instance of a subclass of the ClassInfo class, Returns True. If object is not a given type, the returned result is always false. If ClassInfo does not represent a class (type Object), then it is either a tuple of a class or recursively contains such a tuple of data types. Other sequence types are not allowed. If ClassInfo is not a data type or a tuple of data types, a TypeError exception is thrown.

function: to determine whether an object is a known type.

Its first argument (object) is the second parameter (type) is the type name (int ...). Or a list of type names ((int,list,float) is a list). Its return value is Boolean (True or flase).

Returns true if the type of the object is the same as the type of parameter two. If parameter two is a tuple, returns true if the object type is the same as one of the type names in the tuple.

Example:>>> isinstance (1, int) true>>> isinstance (1.0, float) True >>> a = 4
>>> isinstance (A,int)
True
>>> isinstance (A,STR)
False
>>> Isinstance (A, (str,int,list))
True>>>isinstance (a,dict) Determines whether object A is a dictionary, if true, prints true, such as false, to print false. The difference between type () and Isinstance ():

Common denominator: Both can determine the object type

Isinstance () differs from type ():

• Type () does not consider a subclass to be a parent class type, regardless of the inheritance relationship.

• Isinstance () considers the subclass to be a type of parent class, considering the inheritance relationship.

It is recommended to use Isinstance () if you want to determine whether two types are the same.

Different points: For a class class of subclass object type judgment, type is not, and isinstance can.

For example:

class a:passclass b (a): Passisinstance (a (), a) # returns  Truetype (a ()) = = A # returns trueisinstance (B (), a) # returns truetype (b ()) = = a # returns false      

• In conclusion, it is recommended to use Isinstance to determine the object type.

Isalpha returns a non-zero if it is a letter, otherwise returns to 0

Isalnum returns a non-zero if it is a letter or number, otherwise returns 0

IsDigit if the number (0-9) returns a non-zero; otherwise returns 0

#!/usr/bin/python #-*-coding:utf-8-*- str = "this2009"; # no spaces in characters < Span class= "Hl-code" > print str. Isalnum < Span class= "Hl-code" > str = "this is string EXAMPLE....WOW!!! < Span class= "hl-quotes" > < Span class= "hl-reserved" >print str.isalnum

The result of the above example output is as follows:

TrueFalse

Python built-in function isinstance usage and differences from type