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Does Python determine the type of a variable?

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Release： 2019-07-29 09:52:40

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Does Python determine the type of a variable?

Python’s data types include: numbers (int), floating point (float), strings (str), lists (list), tuples (tuple), and dictionaries (dict) , Set (set)

is generally judged through the following methods:

1. isinstance(parameter 1, parameter 2)

Description: This function is used to judge a variable ( Parameter 1) Whether it is a known variable type (Parameter 2) similar to type()

Parameter 1: Variable

Parameter 2: It can be a direct or indirect class name, basic type or by The tuple they consist of.

Return value: If the type of the object is the same as the type of parameter two (classinfo), it returns True, otherwise it returns False

Example:

#判断变量类型的函数
def typeof(variate):
    type=None
    if isinstance(variate,int):
        type = "int"
    elif isinstance(variate,str):
        type = "str"
    elif isinstance(variate,float):
        type = "float"
    elif isinstance(variate,list):
        type = "list"
    elif isinstance(variate,tuple):
        type = "tuple"
    elif isinstance(variate,dict):
        type = "dict"
    elif isinstance(variate,set):
        type = "set"
    return type
# 返回变量类型
def getType(variate):
    arr = {"int":"整数","float":"浮点","str":"字符串","list":"列表","tuple":"元组","dict":"字典","set":"集合"}
    vartype = typeof(variate)
    if not (vartype in arr):
        return "未知类型"
    return arr[vartype]
    
#判断变量是否为整数
money=120
print("{0}是{1}".format(money,getType(money)))
#判断变量是否为字符串
money="120"
print("{0}是{1}".format(money,getType(money)))
money=12.3
print("{0}是{1}".format(money,getType(money)))
#判断变量是否为列表
students=[&#39;studentA&#39;]
print("{0}是{1}".format(students,getType(students)))
#判断变量是否为元组
students=(&#39;studentA&#39;,&#39;studentB&#39;)
print("{0}是{1}".format(students,getType(students)))
#判断变量是否为字典
dictory={"key1":"value1","key2":"value2"}
print("{0}是{1}".format(dictory,getType(dictory)))
#判断变量是否为集合
apple={"apple1","apple2"}
print("{0}是{1}".format(apple,getType(apple)))

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Return:

Does Python determine the type of a variable?

2. By comparing with constants of known types

Example:

#判断变量类型的函数
def typeof(variate):
    type1 = ""
    if type(variate) == type(1):
        type1 = "int"
    elif type(variate) == type("str"):
        type1 = "str"
    elif type(variate) == type(12.3):
        type1 = "float"
    elif type(variate) == type([1]):
        type1 = "list"
    elif type(variate) == type(()):
        type1 = "tuple"
    elif type(variate) == type({"key1":"123"}):
        type1 = "dict"
    elif type(variate) == type({"key1"}):
        type1 = "set"
    return type1
# 返回变量类型
def getType(variate):
    arr = {"int":"整数","float":"浮点","str":"字符串","list":"列表","tuple":"元组","dict":"字典","set":"集合"}
    vartype = typeof(variate)
    if not (vartype in arr):
        return "未知类型"
    return arr[vartype]
    
#判断变量是否为整数
money=120
print("{0}是{1}".format(money,getType(money)))
#判断变量是否为字符串
money="120"
print("{0}是{1}".format(money,getType(money)))
money=12.3
print("{0}是{1}".format(money,getType(money)))
#判断变量是否为列表
students=[&#39;studentA&#39;]
print("{0}是{1}".format(students,getType(students)))
#判断变量是否为元组
students=(&#39;studentA&#39;,&#39;studentB&#39;)
print("{0}是{1}".format(students,getType(students)))
#判断变量是否为字典
dictory={"key1":"value1","key2":"value2"}
print("{0}是{1}".format(dictory,getType(dictory)))
#判断变量是否为集合
apple={"apple1","apple2"}
print("{0}是{1}".format(apple,getType(apple)))

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Return:

1118859-20180719111155592-1613687455 (1).png

Supplement:

The difference between isinstance() and type():

type() does not consider the subclass to be a parent class type and does not consider the inheritance relationship.

isinstance() will consider the subclass to be a parent class type and consider the inheritance relationship.

If you want to determine whether two types are the same, it is recommended to use isinstance().

Related tutorial recommendations: Python video tutorial

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