python入门到放弃-基本数据类型之tuple元组
guoke-boy 人气:4#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
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