random
我们经常看到网站的随机验证码，这些都是由随机数生成的，因此我们需要了解一下随机数的模块。如何生成随机数。
random 生成随机数
random.random() 生成0-1之间的小数
>>> import random
>>> random.random()
0.7386445925394346
random.randint(1,3) 生成1-3之间的整数随机数
>>> random.randint(1,5)
4
>>> random.randint(1,5)
5
randrange(self,start,stop=None,step=1,_int=int) def randrange(self, start, stop=None, step=1, _int=int):
"""Choose a random item from range(start, stop[, step]).
This fixes the problem with randint() which includes the
endpoint; in Python this is usually not what you want.
"""
# This code is a bit messy to make it fast for the
# common case while still doing adequate error checking.
randrange(self,start,stop,sep)生成随机数，可以定义步长。
>>> random.randrange(1,9,2)
3
>>> random.randrange(1,8,2)
1
>>> random.randrange(1,8,2)
3
生成5位随机数，例：
>>> random_num = random.randint(10000,99999)
>>> random_num
90821
方法二：
import random
nums = []
for i in range(5):
if i == random.randint(1,5):
nums.append(str(i))
else:
nums.append(chr(random.randint(65,90)))
else:
print("".join(nums))
运行结果如下：
CU23M