Isinstance() function usage

  isinstance() Function to determine whether an object is a known type , It is usually used to judge whether two types are the same .

example :

1. When you type x < y when ,num Of Ternary expression return x Value by 100, Its type passes int After the transformation , and isinstance Of classinfo params “int” Contrast type , So it is concluded that by “ True"

2. contrary , When you type x < y when ,num Of Ternary expression return " x < y " , The type of “str”, and isinstance Of classinfo params “int” Contrast type , So it is concluded that by “ False"

3. When you type x < y when ,num Of Ternary expression return “False” , and isinstance Of classinfo params “int” Contrast type , because False It can also be understood as equivalent to 0, and int Type match , So it is concluded that by “ True" .

4. When you type x < y when ,num Of Ternary expression return “False” , and isinstance Of classinfo params “str” Contrast type , because False It belongs to bool Boolean type , Many times, it will be accidentally misunderstood as str. So it is concluded that by “ False " .

5. When you type x < y when ,num Of Ternary expression return “False” , and isinstance Of classinfo params “bool” Contrast type , So it is concluded that by “ True" .

Be careful ： params in , If classinfo Type is string , It has to be for str, If written string, Will report a mistake .

type() And isinstance() difference :

establish Thursday class and Inherit Thursday Of Friday

print(isinstance(Thursday(),Thursday)) # The output is True


print(type(Thursday()) == Thursday) # The output is True


print(isinstance(Friday(),Thursday)) # The output is True, Friday() Inherited from Thursday

print(type(Friday()) == Thursday) # The output is False, type() Function does not recognize subclasses , Inheritance relationship of parent class