Python isinstance() 方法

Python isinstance()函数如果对象是指定类型则返回 True，如果不匹配则返回 False。

Syntax : isinstance(obj, class)

Parameters : 

• obj : The object that need to be checked as a part of class or not.
• class : class/type/tuple of class or type, against which object is needed to be checked.

Returns : True, if object belongs to the given class/type if single class is passed or any of the class/type if tuple of class/type is passed, else returns False. Raises

TypeError: if anything other than mentioned valid class type. 

Python isinstance() 示例

示例 1：带有 int 和 list 的Python isinstance

Python3

# Python 3 code to demonstrate
# working of isinstance()
# with native types
 
# initializing native types
test_int = 5
test_list = [1, 2, 3]
 
# testing with isinstance
print("Is test_int integer? : " + str(isinstance(test_int, int)))
print("Is test_int string? : " + str(isinstance(test_int, str)))
print("Is test_list integer? : " + str(isinstance(test_list, int)))
print("Is test_list list? : " + str(isinstance(test_list, list)))
 
# testing with tuple
print("Is test_int integer or list or string? : "
      + str(isinstance(test_int, (list, int))))

输出：

Is test_int integer? : True
Is test_int string? : False
Is test_list integer? : False
Is test_list list? : True
Is test_int integer or list or string? : True

示例 2：演示 isinstance() 与对象的使用

Python3

# Python 3 code to demonstrate
# working of isinstance()
# with objects
 
# declaring classes
class gfg1:
    a = 10
 
# inherited class
class gfg2(gfg1):
    string = 'GeeksforGeeks'
 
 
# initializing objects
obj1 = gfg1()
obj2 = gfg2()
 
# checking instances
print("Is obj1 instance of gfg1? : " + str(isinstance(obj1, gfg1)))
print("Is obj2 instance of gfg2? : " + str(isinstance(obj2, gfg2)))
print("Is obj1 instance of gfg2? : " + str(isinstance(obj1, gfg2)))
 
 
# check inheritance case
# return true
print("Is obj2 instance of gfg1? : " + str(isinstance(obj2, gfg1)))

输出：

Is obj1 instance of gfg1? : True
Is obj2 instance of gfg2? : True
Is obj1 instance of gfg2? : False
Is obj2 instance of gfg1? : True

示例 3： Python isinstance 数组

Python3

test_list = [1, 2, 3]
print ("Is test_list list? : " + str(isinstance(test_list, list)))

输出：

Is test_list list? : True

示例 4： Python isinstance字符串

Python3

test_str = "GeeksforGeeks"
print ("Is test_str string? : " + str(isinstance(test_str, str)))

输出：

Is test_str string? : True

示例 4： Python isinstance 字典

Python3

test_dict = {"apple" : 1, "Ball" : 2 }
print ("Is test_str dictionary? : " + str(isinstance(test_dict, dict)))

输出：

Is test_str dictionary? : True

示例 4： Python isinstace 类方法

Python

class geeks:
    course = 'DSA'
   
    def purchase(obj):
        return obj.course
   
   
geeks.purchase = classmethod(geeks.purchase)
str(isinstance(geeks.purchase(), str ))

输出：

True