python中常用的知识点（三）

import time
t1 = time.time()
s = ""
for i in range(1000000):
    s += "哈哈"
t2 = time.time()
display("用时：" + str(t2-t1))
t3 = time.time()
l = []
for i in range(1000000):
    l.append("哈哈")
m = "".join(l)
t4 = time.time()
display("用时：" + str(t4-t3))

p = 'ab#'
q = 'ab#'
display(id(p),id(q))
# 判断两个对象的值是不是相等；
display(p == q)
# 判断两个对象是不是同一个对象；
display(p is q)

m = '12_abv'
n = '12_abv'
display(id(m))
display(id(n))
display(m == n)
display(m is n)
p = 'ab#'
q = 'ab#'
display(id(p))
display(id(q))
display(p == q)
display(p is q)