+符号拼接 VS ''.join()拼接

import  time   导入时间模块   

time01 = time.time()起始时间 
a=('')
for i  in range(10000000):
    a += "qwe"
time02 = time.time()结束时间 
print("shijin"+str(time02-time01))str转成字符串 (结束时间减起始时间 )

time03=time.time()
c=[]
for i in range(10000000):
    c.append('qwe')
c=''.join(c)
time04=time.time()

print("shijin"+str(time04-time03))