【python】迭代器与嵌套for循环生成密码字典速度对比

前言

分别使用迭代器与嵌套for循环生成包含所有由数字组成的长度为8的密码字典，也就是从00000000到99999999。

代码

• 迭代器

import time
t1 = time.time()
import itertools as its
iterator = its.product('0123456789', repeat=8)
f = open('pwd.txt', 'w')
for i in iterator:
    f.write(''.join(i)+'\n')
f.close()
t2 = time.time()
print(t2-t1)
# 62.58520317077637

• 嵌套for循环

import time
t1 = time.time()
ls = '0123456789'
f = open('pwd.txt', 'w')
for i in ls:
    for j in ls:
        for k in ls:
            for x in ls:
                for y in ls:
                    for z in ls:
                        for m in ls:
                            for n in ls:
                                f.write(i+j+k+x+y+z+m+n+'\n')
f.close()
t2 = time.time()
print(t2-t1)
# 80.10285377502441

对比 总计用时 方法选择用时（单位：秒）迭代器62.58520317077637嵌套for循环80.10285377502441 代码风格

• 迭代器：代码很短，风格良好。
• 嵌套for循环：代码较长，且for循环的层层嵌套导致代码风格很差，不推荐。

结果

对比可见，用迭代器生成密码字典速度更快，且代码风格更加良好。