python判断key是否在字典用in不用has_key

小测试

in

del.py

import datetime
cur = datetime.datetime.now()

num = 1
a_list = {"a":1, "b":2, "c":3}
while num < 100000:
    if "a" in a_list:
        pass
    num += 1

now = datetime.datetime.now()
print (now - cur).total_seconds()

has_key

del2.py

import datetime
cur = datetime.datetime.now()

num = 1
a_list = {"a":1, "b":2, "c":3}
while num < 100000:
    if a_list.has_key("a"):
        pass
    num += 1

now = datetime.datetime.now()
print (now - cur).total_seconds()

结果

$python del.py
0.02399

$python del2.py
0.030393

官网

官方文档推荐用 key in dict 的语法，因为它更短更通俗易懂。has_key是老旧遗留的api，为了支持2.2之前的代码留下的。Python3已经删除了该函数。