Python basic data types based combat deep copy of the [& shallow copy, mutable objects & immutable]

from copy import *




#String 浅复制
aList = [3,5,7]
bList = aList[::]
flag = aList == bList
print(flag)
flag = aList is bList
print(flag)

#Answer
#True
#False











#切片
aList = [3,5,7,9]
aList[:3] = [] #删除列表中前3个元素
print(aList)

#Answer:
#[9]

aList = [3,5,7,9,11]
del aList[:3] #同上
print(aList)

#Answer:
#[9, 11]

#String
#is 用于判断 id是否相同；== 用于判断 值是否相同

astr = "good"
bstr = "good"
cstr = astr + ""
flag_ab = astr is bstr
print(flag_ab)
flag_ab = astr == bstr
print(flag_ab)
flag_ac = astr is cstr
print(flag_ac)
flag_ac = astr == bstr
print(flag_ac)

#Answer:
#True
#True
#True
#True



#基本数据类型
a = 128
b = 128
c = a + 0
d = b + 0
e = a << 1
f = e >> 1
print(id(a))
print(id(b))
print(id(c))
print(id(d))
print(id(e))
print(id(f))

#Answer:
#1514041536
#1514041536
#1514041536
#1514041536
#1514045632
#1514041536







a = ['a','b','c','d']
b = copy(a)
a[0] = 'A'
print('a:', a)
print('b:', b)

#Answer:浅拷贝！ 链表是可变对象，如果不特殊强调，使用的是深拷贝。
#a: ['A', 'b', 'c', 'd']
#b: ['a', 'b', 'c', 'd']

#Answer（如果不使用copy，直接用b=a）：深拷贝！
#a: ['A', 'b', 'c', 'd']
#b: ['A', 'b', 'c', 'd']

#不可变对象用于保障数据的稳定！基本数据类型&String&元组，这些数据时可以用来哈希的
#可变对象用于节省内存！链表、元祖之类！