[Python知识库]python中isinstance()函数用法

isinstance()用来判断一个对象是否是一个已知的类型，isinstance()函数的语法如下：

isinstance(object,classtype)

def isinstance(x, A_tuple): # real signature unknown; restored from __doc__
    """
    Return whether an object is an instance of a class or of a subclass thereof.
    
    A tuple, as in ``isinstance(x, (A, B, ...))``, may be given as the target to
    check against. This is equivalent to ``isinstance(x, A) or isinstance(x, B)
    or ...`` etc.
    """
    pass

isinstance()函数的返回值是布尔型，若object的类型是classtype，那么就返回True，否则返回False。

示例代码：

A = "I love you"
ans = isinstance(A, str)
print("A is str: " + str(ans))

B = ['I love you']
ans = isinstance(B, str)
print("B is str: " + str(ans))

C = ["I love you"]
ans = isinstance(C, list)
print("C is list: " + str(ans))

if not isinstance(C, list):
    print("C is not a list")
else:
    print("C is a list")

运行效果：

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