python内置模块-random

print(random.randint(1,10)) 生成随机整数，下限必须小于上限
print(random.randrange(1,10)) 生成随机整数，参数为（[start],stop,[step]）

random.random()  生成0,1的随机浮点数

随机生成4位验证码:

import random
checkcode = ''
for i in range(4):
    current =random.randrange(0,4)
    if current == 2:
        temp = chr(random.randint(65,90)) #大写字母
    elif current != 3:
        temp = chr(random.randint(97,122)) #小写字母
    else:
        temp = random.randint(0,9)
    checkcode += str(temp)
print(checkcode)