python入门到放弃(六)-基本数据类型之tuple元组

 #概述

元组俗称不可变的列表，又称只读列表，是python的基本数据类型之一， 用()小括号表示，里面使用，逗号隔开

元组里面可以放任何的数据类型的数据，查询可以，循环可以，但是就是不能修改

#先来看看tuple元组的源码写了什么，方法:按ctrl+鼠标左键点tuple

lass tuple(object):
    """
    tuple() -> empty tuple
    tuple(iterable) -> tuple initialized from iterable's items
    
    If the argument is a tuple, the return value is the same object.
    """
    def count(self, value): # real signature unknown; restored from __doc__
        """ T.count(value) -> integer -- return number of occurrences of value """
        return 0

    def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
        """
        T.index(value, [start, [stop]]) -> integer -- return first index of value.
        Raises ValueError if the value is not present.
        """
        return 0

    def __add__(self, y): # real signature unknown; restored from __doc__
        """ x.__add__(y) <==> x+y """
        pass

    def __contains__(self, y): # real signature unknown; restored from __doc__
        """ x.__contains__(y) <==> y in x """
        pass

    def __eq__(self, y): # real signature unknown; restored from __doc__
        """ x.__eq__(y) <==> x==y """
        pass

    def __getattribute__(self, name): # real signature unknown; restored from __doc__
        """ x.__getattribute__('name') <==> x.name """
        pass

    def __getitem__(self, y): # real signature unknown; restored from __doc__
        """ x.__getitem__(y) <==> x[y] """
        pass

    def __getnewargs__(self, *args, **kwargs): # real signature unknown
        pass

    def __getslice__(self, i, j): # real signature unknown; restored from __doc__
        """
        x.__getslice__(i, j) <==> x[i:j]
                   
                   Use of negative indices is not supported.
        """
        pass

    def __ge__(self, y): # real signature unknown; restored from __doc__
        """ x.__ge__(y) <==> x>=y """
        pass

    def __gt__(self, y): # real signature unknown; restored from __doc__
        """ x.__gt__(y) <==> x>y """
        pass

    def __hash__(self): # real signature unknown; restored from __doc__
        """ x.__hash__() <==> hash(x) """
        pass

    def __init__(self, seq=()): # known special case of tuple.__init__
        """
        tuple() -> empty tuple
        tuple(iterable) -> tuple initialized from iterable's items
        
        If the argument is a tuple, the return value is the same object.
        # (copied from class doc)
        """
        pass

    def __iter__(self): # real signature unknown; restored from __doc__
        """ x.__iter__() <==> iter(x) """
        pass

    def __len__(self): # real signature unknown; restored from __doc__
        """ x.__len__() <==> len(x) """
        pass

    def __le__(self, y): # real signature unknown; restored from __doc__
        """ x.__le__(y) <==> x<=y """
        pass

    def __lt__(self, y): # real signature unknown; restored from __doc__
        """ x.__lt__(y) <==> x<y """
        pass

    def __mul__(self, n): # real signature unknown; restored from __doc__
        """ x.__mul__(n) <==> x*n """
        pass

    @staticmethod # known case of __new__
    def __new__(S, *more): # real signature unknown; restored from __doc__
        """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
        pass

    def __ne__(self, y): # real signature unknown; restored from __doc__
        """ x.__ne__(y) <==> x!=y """
        pass

    def __repr__(self): # real signature unknown; restored from __doc__
        """ x.__repr__() <==> repr(x) """
        pass

    def __rmul__(self, n): # real signature unknown; restored from __doc__
        """ x.__rmul__(n) <==> n*x """
        pass

    def __sizeof__(self): # real signature unknown; restored from __doc__
        """ T.__sizeof__() -- size of T in memory, in bytes """
        pass

tuple

#判断是否是元组

print((3))   #不是元组
tu = (3, )   #元组中如果只有一个元素，需要在括号里写一个，逗号，否则就不是元组
tu = tuple() #空元组写法
print(type(tu))  #<class 'tuple'>

#验证元组不能增删改，查看索引就可以

tu = ("人民币","美元","美金","欧元")

tu.append("张三") #不允许添加：tuple' object has no attribute 'append'

tu[0] = "日元"    #不允许修改 :object does not support item assignment

del tu[2]        #报错，不允许删除：'tuple' object doesn't support item deletion

print(tu[2]) #索引就可以
#欧元

#关于元组不可变的注意点

这里元组的不可变意思是子元素不可变，但是子元素内容的子元素是可以变的，这要取决子元素本身是否是可变

#例子:

# 因为列表是可变长类型，所以可以在里面增加 tu = (1,"蒋小鱼","鲁炎",[]) tu[3].append("张冲") print(tu)
# (1, '蒋小鱼', '鲁炎', ['张冲'])

#需要注意的是，元组的第一层是不能进行赋值的，内部元素是没有要求的
#例子
#tu = (1,"巴朗","项羽","张飞") #像这样子是不能进行赋值的

#元组的索引和切片

tu = (3,4,5,6,7,8)
#索引：下标从0开始找
print(tu[0]) #3
print(tu[1]) #4
#切片
print(tu[1:3]) #(4, 5)

#详细使用可参考str字符串篇