import random
check=‘‘
for num in range(4):
    i = random.randrange(1,3)                 #随机生成1或者2
    if i%2==0:                                #判断后选择生成字母
        check_num = random.randrange(65,91)
        check_str = chr(check_num)
        check=check + check_str
    else:                                     #生成数字
        check_num = random.randrange(49,58)
        check_str = chr(check_num)
        check=check + check_str
print (check)

python随机生成四位验证码