python内存-fromkeys

fromkeys

这个方法涉及到可变不可变类型，记录下测试代码

不可变类型

#可变类型-list
x=["zx","zx2","zx3"]
dic=dict.fromkeys(x,[])
dic["zx"].append("x")
#打印dict中的list id
print(id(dic["zx"]))
print(id(dic["zx3"]))
print(id(dic["zx2"]))
print(dic)

1540977509576
1540977509576
1540977509576
{'zx': ['x'], 'zx2': ['x'], 'zx3': ['x']}

可变类型

#可变类型-list
x=["zx","zx2","zx3"]
dic=dict.fromkeys(x,1)
dic["zx"]=2
#打印dict中的list id
print(id(dic["zx"]))
print(id(dic["zx3"]))
print(id(dic["zx2"]))
print(dic)

2004250112
2004250080
2004250080
{'zx': 2, 'zx2': 1, 'zx3': 1}