Python字符串通过'+'和join函数拼接新字符串的性能测试比较

def strTest(num):  s = 'Hello'  for i in range(num):    s += 'x'  return s

def strTest2(num):  s = 'Hello'  l = list(s)  for i in range(num):    l.append('x')  return ''.join(l)

>>> def strTest1(num):...   s = 'Hello'...   for i in range(num):...     s += 'x'...   return s>>> def strTest2(num):...   s = 'Hello'...   l = list(s)...   for i in range(num):...     l.append(s)...   return ''.join(l)>>>>>> from timeit import timeit# 运行10万级别数据，运行速度比对>>> timeit("strTest1(100000)", setup="from __main__ import strTest1", number=1)0.016680980406363233>>> timeit("strTest2(100000)", setup="from __main__ import strTest2", number=1)0.009688869110618725# 运行100万级别数据，运行速度比对>>> timeit("strTest1(1000000)", setup="from __main__ import strTest1", number=1)0.14558920607187195>>> timeit("strTest2(1000000)", setup="from __main__ import strTest2", number=1)0.1335057276853462# 运行1000万级别数据，运行速度比对>>> timeit("strTest1(10000000)", setup="from __main__ import strTest1", number=1)5.9497953107860475>>> timeit("strTest2(10000000)", setup="from __main__ import strTest2", number=1)1.3268972136649921# 运行2000万级别数据，运行速度比对>>> timeit("strTest1(20000000)", setup="from __main__ import strTest1", number=1)21.661270140499056>>> timeit("strTest2(20000000)", setup="from __main__ import strTest2", number=1)2.6981786518920217# 运行3000万级别数据，运行速度比对>>> timeit("strTest1(30000000)", setup="from __main__ import strTest1", number=1)49.858089123966295>>> timeit("strTest2(30000000)", setup="from __main__ import strTest2", number=1)4.285787770209481# 运行4000万级别数据，运行速度比对>>> timeit("strTest1(40000000)", setup="from __main__ import strTest1", number=1)86.67876273457563>>> timeit("strTest2(40000000)", setup="from __main__ import strTest2", number=1)5.328653452047092# 运行5000万级别数据，运行速度比对>>> timeit("strTest1(50000000)", setup="from __main__ import strTest1", number=1)130.59138063819023>>> timeit("strTest2(50000000)", setup="from __main__ import strTest2", number=1)6.8375931077291625# 运行6000万级别数据，运行速度比对>>> timeit("strTest1(60000000)", setup="from __main__ import strTest1", number=1)188.28227241975003>>> timeit("strTest2(60000000)", setup="from __main__ import strTest2", number=1)8.080144489401846# 运行7000万级别数据，运行速度比对>>> timeit("strTest1(70000000)", setup="from __main__ import strTest1", number=1)256.54383904350277>>> timeit("strTest2(70000000)", setup="from __main__ import strTest2", number=1)9.387400816458012# 运行8000万级别数据，运行速度比对>>> timeit("strTest1(80000000)", setup="from __main__ import strTest1", number=1)333.7185806572388>>> timeit("strTest2(80000000)", setup="from __main__ import strTest2", number=1)10.946627677462857